This is a genuine Milwaukee replacement part. The lock washer may be found in a variety of power tools and equipment. This is a metal part, generally used to secure the connection with a screw or bolt, and to prevent inadvertent loosening. It may be used in various locations in the machine, depending on model. Please be aware that the...Read morere are different washers used in the machine. Refer to the parts diagram to be sure of ordering the correct part. You may require a screwdriver or wrench when replacing this part. This item is sold individually.