Standard Click Rule

This efficient, tactile, extension measuring tool is a favorite with blind carpenters. It measures items with an accuracy to within 1/16 of an inch. The base unit, which measures up to 12 inches, consists of four major parts: 1/2-inch aluminum tube, sliding threaded rod, locking screw, and two 1/4-inch-thick metal stops. The sliding threaded rod, which measures up to 6 inches, is marked with raised lines in 1/2-inch intervals on the top and 1/16-inch intervals on the side. Each 1/16-inch movement of the rod also makes a clicking sound. The addition of multiple 12-inch extensions allows for the measurement of longer spans.