Unbreakable plastic, with textured surface for non-slip grip. Specially shaped to fit the hand for working comfort even over long periods. Hole at top permits convenient hand-up storage. Tang-gripping insert is tempered metal, with two threaded sections of different diameters. This assures proper alignment and positive hold for files, and also allows handle to be reused. Simply unscrew the file in use and insert a new one. Refer to separate charts below for Swiss Prescision and American Pattern files.