Profile Bus 51 mm strenghtened with three Grooves under the Bolt M8 Head, Oval Nut 12x25 M6 or M8. Profile 51 mm is used for mounting in Assembly and Milling Tables as Guide Rails for moving or mounting of Stops, Limiters, Arm Cramps, Clamps and other Accessories on them. Compatible with 13mm Profile Slider. It has Groove for mounting of Dimension Scale.