This needle roller bearing guides a shaft or stud directly on a track surface through a single row of needle rollers running against a particularly thick-walled outer ring. The outer diameter is 32.0 mm and the net mass is 47.71 g. RSTO12 is built without an inner ring — the needle roller and cage assembly runs directly on the shaft, and the outer ring, needle roller and cage assembly can be mounted separately, giving flexibility during assembly. The design has no axial guidance of the outer ring, so axial location must be provided by the surrounding construction. The bearing is open and supplied without sealing, which means the mounting environment must keep contaminants away from the raceway and provide adequate lubrication. Since RSTO12 has no inner ring, the shaft or pin it runs on must be hardened and ground to serve as the raceway. The construction suits applications where a compact, thick-walled outer ring must carry radial load while running against a track, with axial positioning handled externally.