it's a MIDI Registered Parameter Number (RPN)
I'm sure you'll find more detail on the web, but you basically send 2 CCs (0x64 and 0x65), to set which parameter to change, then Two other CCs (0x06 and if needed 0x26) to set the value.
To update Microbrute Bend range you need to send:
B0 65 00 Controller/chan 0, RPN coarse (101), Pitch Bend Range
B0 64 00 Controller/chan 0, RPN fine (100), Pitch Bend Range
B0 06 xx Controller/chan 0, Data Entry coarse, +/- xx semitones (from 1 to 12)
(B0 26 04 Controller/chan 0, Data Entry fine), -> Not implemented/needed on MicroBrute do not send