Strong compression springs are used to expand the unit. Sized to fit a 6" vise. Durable all metal construction. The unit can be disassembled for cleaning. *** PLEASE SEE SCROLL DOWN FOR MORE DETAILS. *** The Parallel Separator by Edge Technology is designed to firmly hold the parallel bars against the vise jaws during machining operations. This configuration prevents chips from being logged between the parallels and the bed of the vise and eliminates the need to clean the parallel bars every time the workpiece is removed from the vise.