These washers are used wherein space limitations demand one side to be clipped. Clipped hardened washers offer a smooth bearing surface. They are used at the base of the head of a bolt / nut. The mechanical, chemical, and dimensional requirements in terms of hardened washers are covered under ASTM specification F436. These washers are thoroughly hardened or carburized in order to add strength; however, they are physically smaller compared to standard F844 flat washers.