This is a holder for the Apple AirTag that mounts under the bottle holder on your bike. It uses 2x M5 25mm long bolts for mounting. The holes are 73mm (outer wall) and 57mm (inner wall) apart. It is 11mm thick.
AirTag_Bottom_Longer and AirTag_Top_Longer with longer holes for the bolts (42mm inner wall) have been added.