Specifies internal and external tooth lock washers suitable for use in normal, over-the-thread applications, and also for use as a washer component of a screw and captive washer assembly. It covers washers intended for assembly with threaded fasteners with either metric coarse pitch series threads, or with spaced tapping screw threads. It gives dimensional, material, mechanical property, finish and testing requirements, and also testing procedures, and generally covers a diameter range 3-30 mm for metric coarse pitch fasteners, and 2.9 (No. 4) to 8.0 (No. 16) for fasteners with spaced tapping screw threads. Four types of washers are given, viz. external, internal, countersunk external, and internal/external.