This roller guides motion along a track using a double row angular contact ball bearing arrangement built into a stud-type body with an outside diameter of 80.0 mm and a width of 91.0 mm, weighing 1.2 kg net. The outer ring is particularly thick-walled and self-retaining together with the ball and cage assembly, with axial guidance of the outer ring provided by the balls themselves. The unit has a solid, long roller stud with external thread and no eccentric collar, and includes an assembling aid hexagonal socket only on the flange side end face. Sealing is provided by lip seals on both sides (2RS), giving axial sealing action and keeping contamination out of the rolling elements. There is no relubrication facility, so the internal grease fill must last for the service life of the unit. The design suits mounting directly onto a fixed axis where the outer ring itself acts as the running surface against a mating track.