This is a track roller complete with stud instead of inner ring, which is designed to operate with its outer ring rolling on the track. These NTN stud type track rollers are applied to eccentric roller, guide roller, rocker arm roller and more. similarly to the roller followers. One end of the stud is threaded and the hexagonal nut is used to be mounted easily. NTN Cam Follower, Cylindrical OD, Series: NUKR, 40 mm Roller Dia, 21.5 mm Roller Width, 18 mm Stud Dia, 36.5 mm Stud Length, M18 x 1.6, 19 mm Thread Length, 24100 N Dynamic/29100 N Static, 4700 RPM Grease Maximum, -40 to 120 °C, Standard Stud, Shielded Closure, Hex, Through Hardened Steel Roller