The Starrett Adjustable Parallel provides a wide range of use in layout, gaging, inspection work and for setups on various machine tools. Its adjustable feature makes it possible to adjust it to exact size by micrometer measurement and also permits use in place of several solid-type parallels. The parallel is useful as a gage in checking the size of slots and openings. It is also convenient for use in machine vises, for leveling or adjusting work on setups of milling and grinding machines, shapers, planers, drill presses and for many other applications. The parallel slides smoothly and can be easily adjusted. The smaller sizes A, B, and C, are locked by one screw while the larger size, D, has two lock screws. The parallel is 9/32" (7mm) thick. SET of 4 Parallels, Sizes A/B/C/D in Case The parallel is 9/32" (7mm) thick.