The Starrett 384 Steel Parallel is hardened and ground to close limits. It is indispensable for inspection and layout work or for various setups on drill presses, milling and grinding machines, shapers, and so on. Furnished in pairs, 6" length, it is made from a special grade of tool steel, hardened and accurately ground on the four sides. In tool rooms or machine shops, several pairs of these parallels will be of great value. Pair: 3/8" (10mm) Thick, 3/4" (19mm) Width.