In THK LM Roller Accessories have 2 different type: Spring Pax model PA and Fixture  Models SM/SMB and SE/SEB, each type have different usefull. By attaching this spring pad to the back of the LM Roller and turning the adjustment bolt, adjustment of a clearance and a preload can easily be done. For fixter, use of fixture model SM or SE eliminates the need to machine thin tapped holes for mounting the LM Roller, and allows the roller to firmly be secured. Models SE and SEB each have a special rubber wiper with double lips to achieve a high contamination protection effect.