Metric Stud Type Track Roller Bearings can have a parallel or crowned outer ring and a heavy-section outer, with a roller cage and a fixing thread. Some ranges are sealed as standard, others are also available in an open design. Cam followers (stud-type track rollers) are designed to run on tracks and are normally used on cam drives, conveyor systems etc.They are normally either needle or cylindrical roller bearings inside, but instead of an inner ring, they have a solid threaded stud.