Purchase includes one replacement Pitlock wheel pressure washer. The compression washer is installed between the bicycle frame and the lock mechanism housing, and is a critical piece of the Pitlock closure. The fluting assures that the lock has the grip required to function.
Please note that this product is not intended for use with seat skewers. Pitlock seat skewers require a different pressure washer, which can be found here.
Compression washers are made of high quality, stainless steel.