Objects with object paths starting with /org/freedesktop/UDisks2/block_devices/ all represent block devices. Such objects implement the org.freedesktop.UDisks2.Block D-Bus interface and may optionally implement other D-Bus interfaces such as org.freedesktop.UDisks2.Block.ZRAM, org.freedesktop.UDisks2.Filesystem, org.freedesktop.UDisks2.Partition or org.freedesktop.UDisks2.Loop depending on the block device in question.

Note that interfaces may be added and removed at run-time. For example, if a block device is full of zeroes (or, at least, have zeroes in the known metadata areas), it will not initially implement the org.freedesktop.UDisks2.Filesystem interface; however, if a filesystem is later created on the device (using, say, the mkfs(8) command) and the filesystem is recognized by the OS (specifically, recognized by udev(7) and its device probers), the object will gain the interface. If the device is later zeroed or formatted for use as e.g. swap-space, it will lose the org.freedesktop.UDisks2.Filesystem interface.