This is a 3/4" wide x 3/8" thick (19 x 9.5mm), 320mm long bar. It is made to fit the UJK Technology precision mitre gauge in place of the standard 458mm bar. This bar features a grub screw on either side of the locking washer. Tightening the grub screws will lock your mitre fence firmly in position. The shorter length makes it easier to use machines with smaller machine tables. For example used on a disc sander this would give you the option of a sliding fence or a fixed angle fence.