A washer is a thin, disc-shaped plate with a hole in the middle, typically used in conjunction with a threaded fastener. Generally they are made of metal, though plastic washers are not uncommon. When using screws and other threaded fasteners, it is usually a good idea to include a washer for one or more of three main reasons. Washers may serve to:

- Spread a load and prevent surface damage (plain washer)

- Prevent loosening caused by vibrations (spring washer)

- Prevent loosening caused by rotation of the screw/fastener (locking washer)

Some specialized washers may have other functions, but these three comprise a washer’s general purpose.

The G3 grip screw washer is a locking washer manufactured by Heckler & Koch for use exclusively with the G3 grip screw, a screw that secures the rifle’s pistol grip to the lower receiver/trigger pack. Specifically, this washer is a toothed locking, or serrated, washer. It has teeth, or serrations, that extend inward and serve to sink into a bearing surface, in this case the underside of the screw’s head. This prevents any loosening of the G3 grip screw. This may also serve to preserve the threading on the G3 grip screw, as the screw is subject to inertia during the firearm’s operation. With a locking G3 grip screw washer, the screw is less likely to loosen during firing.

For $2.95, you will receive two G3 grip screw washers.