50 mm x 66 mm x 8 mm IKO CRBS 508 A UU thrust roller bearings

Online shopping 50 mm x 66 mm x 8 mm IKO CRBS 508 A UU thrust roller bearings from a great NTN Driveshaft CORP. selection 16mm N at Store. 18.2 kN C0 ... Thrust Roller Bearings 50 mm x 66 mm x 8 mm Accessories.

What is CRBS 508 A UU bearing interchange？