F623RS bearings are used to route belts, 4 near the AB motors, 2 on the belt tensioner, and 4 on the bearing tower (2 are live, 2 are just used for spacing).

Sometimes used in conjunction with the M3 Washers to constrain the belt.

Dimension Measurement
Inner Diameter (ID) 3 mm
Outer Diameter (OD) 10 mm
Width 4 mm
Flange Width (FW) 1 mm