Also known as eccentric track rollers, the shoulder adjusts up or down to align to your track, enabling uniform alignment among rollers in a system. Rollers are for use with Angle Rails for V-Groove Track Rollers. They handle radial and thrust (top and side) loads and work well in dirty environments because debris falls off the angled rail. Secure the stud with a nut for through-hole mounting. All rollers are permanently lubricated.