diff --git a/lib/logitech_receiver/common.py b/lib/logitech_receiver/common.py
index 14dfb2e5..a55f8df1 100644
--- a/lib/logitech_receiver/common.py
+++ b/lib/logitech_receiver/common.py
@@ -18,8 +18,11 @@ from __future__ import annotations
 
 import binascii
 import dataclasses
+import typing
 
 from enum import IntEnum
+from typing import Generator
+from typing import Iterable
 from typing import Optional
 from typing import Union
 
@@ -27,6 +30,9 @@ import yaml
 
 from solaar.i18n import _
 
+if typing.TYPE_CHECKING:
+    from logitech_receiver.hidpp20_constants import FirmwareKind
+
 LOGITECH_VENDOR_ID = 0x046D
 
 
@@ -502,6 +508,31 @@ class NamedInts:
         return isinstance(other, self.__class__) and self._values == other._values
 
 
+def flag_names(enum_class: Iterable, value: int) -> Generator[str]:
+    """Extracts single bit flags from a (binary) number.
+
+    Parameters
+    ----------
+    enum_class
+        Enum class to extract flags from.
+    value
+        Number to extract binary flags from.
+    """
+    indexed = {item.value: item.name for item in enum_class}
+
+    unknown_bits = value
+    for k in indexed:
+        # Ensure that the key (flag value) is a power of 2 (a single bit flag)
+        assert bin(k).count("1") == 1
+        if k & value == k:
+            unknown_bits &= ~k
+            yield indexed[k].lower()
+
+    # Yield any remaining unknown bits
+    if unknown_bits != 0:
+        yield f"unknown:{unknown_bits:06X}"
+
+
 class UnsortedNamedInts(NamedInts):
     def _sort_values(self):
         pass
@@ -543,9 +574,16 @@ class KwException(Exception):
             return self.args[0].get(k)  # was self.args[0][k]
 
 
+class FirmwareKind(IntEnum):
+    Firmware = 0x00
+    Bootloader = 0x01
+    Hardware = 0x02
+    Other = 0x03
+
+
 @dataclasses.dataclass
 class FirmwareInfo:
-    kind: str
+    kind: FirmwareKind
     name: str
     version: str
     extras: str | None
diff --git a/lib/logitech_receiver/device.py b/lib/logitech_receiver/device.py
index 62b759f9..7ee9b85e 100644
--- a/lib/logitech_receiver/device.py
+++ b/lib/logitech_receiver/device.py
@@ -14,10 +14,14 @@
 ## You should have received a copy of the GNU General Public License along
 ## with this program; if not, write to the Free Software Foundation, Inc.,
 ## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+from __future__ import annotations
+
 import errno
 import logging
 import threading
 import time
+import typing
 
 from typing import Any
 from typing import Callable
@@ -37,6 +41,9 @@ from .common import Alert
 from .common import Battery
 from .hidpp20_constants import SupportedFeature
 
+if typing.TYPE_CHECKING:
+    from logitech_receiver import common
+
 logger = logging.getLogger(__name__)
 
 _hidpp10 = hidpp10.Hidpp10()
@@ -265,7 +272,7 @@ class Device:
         return self._kind or "?"
 
     @property
-    def firmware(self):
+    def firmware(self) -> tuple[common.FirmwareInfo]:
         if self._firmware is None and self.online:
             if self.protocol >= 2.0:
                 self._firmware = _hidpp20.get_firmware(self)
diff --git a/lib/logitech_receiver/hidpp10.py b/lib/logitech_receiver/hidpp10.py
index a10d3ca4..6d4ee957 100644
--- a/lib/logitech_receiver/hidpp10.py
+++ b/lib/logitech_receiver/hidpp10.py
@@ -25,8 +25,8 @@ from . import common
 from .common import Battery
 from .common import BatteryLevelApproximation
 from .common import BatteryStatus
+from .common import FirmwareKind
 from .hidpp10_constants import Registers
-from .hidpp20_constants import FIRMWARE_KIND
 
 logger = logging.getLogger(__name__)
 
@@ -110,7 +110,7 @@ class Hidpp10:
             device.registers.append(Registers.BATTERY_STATUS)
             return parse_battery_status(Registers.BATTERY_STATUS, reply)
 
-    def get_firmware(self, device: Device):
+    def get_firmware(self, device: Device) -> tuple[common.FirmwareInfo] | None:
         assert device is not None
 
         firmware = [None, None, None]
@@ -125,21 +125,21 @@ class Hidpp10:
         reply = read_register(device, Registers.FIRMWARE, 0x02)
         if reply:
             fw_version += ".B" + common.strhex(reply[1:3])
-        fw = common.FirmwareInfo(FIRMWARE_KIND.Firmware, "", fw_version, None)
+        fw = common.FirmwareInfo(FirmwareKind.Firmware, "", fw_version, None)
         firmware[0] = fw
 
         reply = read_register(device, Registers.FIRMWARE, 0x04)
         if reply:
             bl_version = common.strhex(reply[1:3])
             bl_version = f"{bl_version[0:2]}.{bl_version[2:4]}"
-            bl = common.FirmwareInfo(FIRMWARE_KIND.Bootloader, "", bl_version, None)
+            bl = common.FirmwareInfo(FirmwareKind.Bootloader, "", bl_version, None)
             firmware[1] = bl
 
         reply = read_register(device, Registers.FIRMWARE, 0x03)
         if reply:
             o_version = common.strhex(reply[1:3])
             o_version = f"{o_version[0:2]}.{o_version[2:4]}"
-            o = common.FirmwareInfo(FIRMWARE_KIND.Other, "", o_version, None)
+            o = common.FirmwareInfo(FirmwareKind.Other, "", o_version, None)
             firmware[2] = o
 
         if any(firmware):
diff --git a/lib/logitech_receiver/hidpp20.py b/lib/logitech_receiver/hidpp20.py
index 8861ec6e..459408d1 100644
--- a/lib/logitech_receiver/hidpp20.py
+++ b/lib/logitech_receiver/hidpp20.py
@@ -23,6 +23,7 @@ import threading
 
 from typing import Any
 from typing import Dict
+from typing import Generator
 from typing import List
 from typing import Optional
 from typing import Tuple
@@ -39,13 +40,13 @@ from . import special_keys
 from .common import Battery
 from .common import BatteryLevelApproximation
 from .common import BatteryStatus
+from .common import FirmwareKind
 from .common import NamedInt
 from .hidpp20_constants import CHARGE_LEVEL
 from .hidpp20_constants import CHARGE_STATUS
 from .hidpp20_constants import CHARGE_TYPE
 from .hidpp20_constants import DEVICE_KIND
 from .hidpp20_constants import ERROR
-from .hidpp20_constants import FIRMWARE_KIND
 from .hidpp20_constants import GESTURE
 from .hidpp20_constants import SupportedFeature
 
@@ -241,8 +242,8 @@ class ReprogrammableKeyV4(ReprogrammableKey):
         self._mapped_to = None
 
     @property
-    def group_mask(self):
-        return special_keys.CID_GROUP_BIT.flag_names(self._gmask)
+    def group_mask(self) -> Generator[str]:
+        return common.flag_names(special_keys.CIDGroupBit, self._gmask)
 
     @property
     def mapped_to(self) -> NamedInt:
@@ -259,7 +260,7 @@ class ReprogrammableKeyV4(ReprogrammableKey):
         if self.group_mask:  # only keys with a non-zero gmask are remappable
             ret[self.default_task] = self.default_task  # it should always be possible to map the key to itself
             for g in self.group_mask:
-                g = special_keys.CID_GROUP[str(g)]
+                g = special_keys.CidGroup[str(g)]
                 for tgt_cid in self._device.keys.group_cids[g]:
                     tgt_task = str(special_keys.TASK[self._device.keys.cid_to_tid[tgt_cid]])
                     tgt_task = NamedInt(tgt_cid, tgt_task)
@@ -515,7 +516,7 @@ class KeysArrayV2(KeysArray):
         self.cid_to_tid = {}
         """The mapping from Control ID groups to Controls IDs that belong to it.
         A key k can only be remapped to targets in groups within k.group_mask."""
-        self.group_cids = {g: [] for g in special_keys.CID_GROUP}
+        self.group_cids = {g: [] for g in special_keys.CidGroup}
 
     def _query_key(self, index: int):
         if index < 0 or index >= len(self.keys):
@@ -543,7 +544,7 @@ class KeysArrayV4(KeysArrayV2):
             self.keys[index] = ReprogrammableKeyV4(self.device, index, cid, tid, flags, pos, group, gmask)
             self.cid_to_tid[cid] = tid
             if group != 0:  # 0 = does not belong to a group
-                self.group_cids[special_keys.CID_GROUP[group]].append(cid)
+                self.group_cids[special_keys.CidGroup(group)].append(cid)
         elif logger.isEnabledFor(logging.WARNING):
             logger.warning(f"Key with index {index} was expected to exist but device doesn't report it.")
 
@@ -1451,7 +1452,7 @@ battery_voltage_remaining = (
 
 
 class Hidpp20:
-    def get_firmware(self, device):
+    def get_firmware(self, device) -> tuple[common.FirmwareInfo] | None:
         """Reads a device's firmware info.
 
         :returns: a list of FirmwareInfo tuples, ordered by firmware layer.
@@ -1471,11 +1472,11 @@ class Hidpp20:
                         if build:
                             version += f".B{build:04X}"
                         extras = fw_info[9:].rstrip(b"\x00") or None
-                        fw_info = common.FirmwareInfo(FIRMWARE_KIND[level], name.decode("ascii"), version, extras)
-                    elif level == FIRMWARE_KIND.Hardware:
-                        fw_info = common.FirmwareInfo(FIRMWARE_KIND.Hardware, "", str(ord(fw_info[1:2])), None)
+                        fw_info = common.FirmwareInfo(FirmwareKind(level), name.decode("ascii"), version, extras)
+                    elif level == FirmwareKind.Hardware:
+                        fw_info = common.FirmwareInfo(FirmwareKind.Hardware, "", str(ord(fw_info[1:2])), None)
                     else:
-                        fw_info = common.FirmwareInfo(FIRMWARE_KIND.Other, "", "", None)
+                        fw_info = common.FirmwareInfo(FirmwareKind.Other, "", "", None)
 
                     fw.append(fw_info)
             return tuple(fw)
diff --git a/lib/logitech_receiver/hidpp20_constants.py b/lib/logitech_receiver/hidpp20_constants.py
index 6fa2b179..abd04d39 100644
--- a/lib/logitech_receiver/hidpp20_constants.py
+++ b/lib/logitech_receiver/hidpp20_constants.py
@@ -15,6 +15,7 @@
 ## with this program; if not, write to the Free Software Foundation, Inc.,
 ## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 from enum import IntEnum
+from enum import IntFlag
 
 from .common import NamedInts
 
@@ -152,7 +153,13 @@ class SupportedFeature(IntEnum):
         return self.name.replace("_", " ")
 
 
-FEATURE_FLAG = NamedInts(internal=0x20, hidden=0x40, obsolete=0x80)
+class FeatureFlag(IntFlag):
+    """Single bit flags."""
+
+    INTERNAL = 0x20
+    HIDDEN = 0x40
+    OBSOLETE = 0x80
+
 
 DEVICE_KIND = NamedInts(
     keyboard=0x00,
@@ -165,7 +172,6 @@ DEVICE_KIND = NamedInts(
     receiver=0x07,
 )
 
-FIRMWARE_KIND = NamedInts(Firmware=0x00, Bootloader=0x01, Hardware=0x02, Other=0x03)
 
 ONBOARD_MODES = NamedInts(MODE_NO_CHANGE=0x00, MODE_ONBOARD=0x01, MODE_HOST=0x02)
 
diff --git a/lib/logitech_receiver/receiver.py b/lib/logitech_receiver/receiver.py
index d0630d60..4748c167 100644
--- a/lib/logitech_receiver/receiver.py
+++ b/lib/logitech_receiver/receiver.py
@@ -15,9 +15,12 @@
 ## with this program; if not, write to the Free Software Foundation, Inc.,
 ## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+from __future__ import annotations
+
 import errno
 import logging
 import time
+import typing
 
 from dataclasses import dataclass
 from typing import Callable
@@ -35,6 +38,9 @@ from .common import Notification
 from .device import Device
 from .hidpp10_constants import Registers
 
+if typing.TYPE_CHECKING:
+    from logitech_receiver import common
+
 logger = logging.getLogger(__name__)
 
 _hidpp10 = hidpp10.Hidpp10()
@@ -145,7 +151,7 @@ class Receiver:
             self.status_callback(self, alert=alert, reason=reason)
 
     @property
-    def firmware(self):
+    def firmware(self) -> tuple[common.FirmwareInfo]:
         if self._firmware is None and self.handle:
             self._firmware = _hidpp10.get_firmware(self)
         return self._firmware
diff --git a/lib/logitech_receiver/special_keys.py b/lib/logitech_receiver/special_keys.py
index 0cce5ba2..281512ec 100644
--- a/lib/logitech_receiver/special_keys.py
+++ b/lib/logitech_receiver/special_keys.py
@@ -19,6 +19,8 @@
 
 import os
 
+from enum import IntEnum
+
 import yaml
 
 from .common import NamedInts
@@ -595,8 +597,30 @@ MAPPING_FLAG = NamedInts(
     persistently_diverted=0x04,
     diverted=0x01,
 )
-CID_GROUP_BIT = NamedInts(g8=0x80, g7=0x40, g6=0x20, g5=0x10, g4=0x08, g3=0x04, g2=0x02, g1=0x01)
-CID_GROUP = NamedInts(g8=8, g7=7, g6=6, g5=5, g4=4, g3=3, g2=2, g1=1)
+
+
+class CIDGroupBit(IntEnum):
+    g1 = 0x01
+    g2 = 0x02
+    g3 = 0x04
+    g4 = 0x08
+    g5 = 0x10
+    g6 = 0x20
+    g7 = 0x40
+    g8 = 0x80
+
+
+class CidGroup(IntEnum):
+    g1 = 1
+    g2 = 2
+    g3 = 3
+    g4 = 4
+    g5 = 5
+    g6 = 6
+    g7 = 7
+    g8 = 8
+
+
 DISABLE = NamedInts(
     Caps_Lock=0x01,
     Num_Lock=0x02,
diff --git a/lib/solaar/cli/show.py b/lib/solaar/cli/show.py
index 79fc3dbe..de0402f0 100644
--- a/lib/solaar/cli/show.py
+++ b/lib/solaar/cli/show.py
@@ -14,6 +14,7 @@
 ## with this program; if not, write to the Free Software Foundation, Inc.,
 ## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+from logitech_receiver import common
 from logitech_receiver import exceptions
 from logitech_receiver import hidpp10
 from logitech_receiver import hidpp10_constants
@@ -149,7 +150,7 @@ def _print_device(dev, num=None):
         for feature, index in dev.features.enumerate():
             flags = dev.request(0x0000, feature.bytes(2))
             flags = 0 if flags is None else ord(flags[1:2])
-            flags = hidpp20_constants.FEATURE_FLAG.flag_names(flags)
+            flags = common.flag_names(hidpp20_constants.FeatureFlag, flags)
             version = dev.features.get_feature_version(int(feature))
             version = version if version else 0
             print("        %2d: %-22s {%04X} V%s    %s " % (index, feature, feature, version, ", ".join(flags)))
diff --git a/tests/logitech_receiver/test_common.py b/tests/logitech_receiver/test_common.py
index 7db1a47c..b4ed9512 100644
--- a/tests/logitech_receiver/test_common.py
+++ b/tests/logitech_receiver/test_common.py
@@ -1,3 +1,5 @@
+from enum import IntFlag
+
 import pytest
 import yaml
 
@@ -121,18 +123,41 @@ def test_named_ints_range():
     assert 6 not in named_ints_range
 
 
-def test_named_ints_flag_names():
-    named_ints_flag_bits = common.NamedInts(one=1, two=2, three=4)
+@pytest.mark.parametrize(
+    "code, expected_flags",
+    [
+        (0, []),
+        (0b0010, ["two"]),
+        (0b0101, ["one", "three"]),
+        (0b1001, ["one", "unknown:000008"]),
+    ],
+)
+def test_named_ints_flag_names(code, expected_flags):
+    named_ints_flag_bits = common.NamedInts(one=0b001, two=0b010, three=0b100)
 
-    flags0 = list(named_ints_flag_bits.flag_names(0))
-    flags2 = list(named_ints_flag_bits.flag_names(2))
-    flags5 = list(named_ints_flag_bits.flag_names(5))
-    flags9 = list(named_ints_flag_bits.flag_names(9))
+    flags = list(named_ints_flag_bits.flag_names(code))
 
-    assert flags0 == []
-    assert flags2 == ["two"]
-    assert flags5 == ["one", "three"]
-    assert flags9 == ["one", "unknown:000008"]
+    assert flags == expected_flags
+
+
+@pytest.mark.parametrize(
+    "code, expected_flags",
+    [
+        (0, []),
+        (0b0010, ["two"]),
+        (0b0101, ["one", "three"]),
+        (0b1001, ["one", "unknown:000008"]),
+    ],
+)
+def test_flag_names(code, expected_flags):
+    class ExampleFlag(IntFlag):
+        one = 0x1
+        two = 0x2
+        three = 0x4
+
+    flags = common.flag_names(ExampleFlag, code)
+
+    assert list(flags) == expected_flags
 
 
 def test_named_ints_setitem():
diff --git a/tests/logitech_receiver/test_hidpp10.py b/tests/logitech_receiver/test_hidpp10.py
index 00ce9ab4..707d521e 100644
--- a/tests/logitech_receiver/test_hidpp10.py
+++ b/tests/logitech_receiver/test_hidpp10.py
@@ -9,7 +9,6 @@ import pytest
 from logitech_receiver import common
 from logitech_receiver import hidpp10
 from logitech_receiver import hidpp10_constants
-from logitech_receiver import hidpp20_constants
 from logitech_receiver.hidpp10_constants import Registers
 
 _hidpp10 = hidpp10.Hidpp10()
@@ -190,18 +189,28 @@ def test_hidpp10_get_battery(device, expected_result, expected_register):
 
 
 @pytest.mark.parametrize(
-    "device, expected_length",
+    "device, expected_firmwares",
     [
-        (device_offline, 0),
-        (device_standard, 3),
+        (device_offline, []),
+        (
+            device_standard,
+            [
+                common.FirmwareKind.Firmware,
+                common.FirmwareKind.Bootloader,
+                common.FirmwareKind.Other,
+            ],
+        ),
     ],
 )
-def test_hidpp10_get_firmware(device, expected_length):
+def test_hidpp10_get_firmware(device, expected_firmwares):
     firmwares = _hidpp10.get_firmware(device)
 
-    assert len(firmwares) == expected_length if expected_length > 0 else firmwares is None
-    for firmware in firmwares if firmwares is not None else []:
-        assert firmware.kind in hidpp20_constants.FIRMWARE_KIND
+    if not expected_firmwares:
+        assert firmwares is None
+    else:
+        firmware_types = [firmware.kind for firmware in firmwares]
+        assert firmware_types == expected_firmwares
+        assert len(firmwares) == len(expected_firmwares)
 
 
 @pytest.mark.parametrize(
diff --git a/tests/logitech_receiver/test_hidpp20_complex.py b/tests/logitech_receiver/test_hidpp20_complex.py
index 1d8c752b..e1d2dfd4 100644
--- a/tests/logitech_receiver/test_hidpp20_complex.py
+++ b/tests/logitech_receiver/test_hidpp20_complex.py
@@ -192,7 +192,7 @@ def test_ReprogrammableKey_key(device, index, cid, tid, flags, default_task, fla
         ),
     ],
 )
-def test_ReprogrammableKeyV4_key(device, index, cid, tid, flags, pos, group, gmask, default_task, flag_names, group_names):
+def test_reprogrammable_key_v4_key(device, index, cid, tid, flags, pos, group, gmask, default_task, flag_names, group_names):
     key = hidpp20.ReprogrammableKeyV4(device, index, cid, tid, flags, pos, group, gmask)
 
     assert key._device == device
diff --git a/tests/logitech_receiver/test_hidpp20_simple.py b/tests/logitech_receiver/test_hidpp20_simple.py
index 43ae4d3f..80cb70c4 100644
--- a/tests/logitech_receiver/test_hidpp20_simple.py
+++ b/tests/logitech_receiver/test_hidpp20_simple.py
@@ -18,6 +18,7 @@ import pytest
 
 from logitech_receiver import common
 from logitech_receiver import hidpp20
+from logitech_receiver import hidpp20_constants
 from logitech_receiver.hidpp20_constants import SupportedFeature
 
 from . import fake_hidpp
@@ -412,3 +413,28 @@ def test_decipher_adc_measurement():
     assert battery.level == 90
     assert battery.status == common.BatteryStatus.RECHARGING
     assert battery.voltage == 0x1000
+
+
+@pytest.mark.parametrize(
+    "code, expected_flags",
+    [
+        (0x01, ["unknown:000001"]),
+        (0x0F, ["unknown:00000F"]),
+        (0xF0, ["internal", "hidden", "obsolete", "unknown:000010"]),
+        (0x20, ["internal"]),
+        (0x33, ["internal", "unknown:000013"]),
+        (0x3F, ["internal", "unknown:00001F"]),
+        (0x40, ["hidden"]),
+        (0x50, ["hidden", "unknown:000010"]),
+        (0x5F, ["hidden", "unknown:00001F"]),
+        (0x7F, ["internal", "hidden", "unknown:00001F"]),
+        (0x80, ["obsolete"]),
+        (0xA0, ["internal", "obsolete"]),
+        (0xE0, ["internal", "hidden", "obsolete"]),
+        (0xFF, ["internal", "hidden", "obsolete", "unknown:00001F"]),
+    ],
+)
+def test_feature_flag_names(code, expected_flags):
+    flags = common.flag_names(hidpp20_constants.FeatureFlag, code)
+
+    assert list(flags) == expected_flags