This is sold as a set that contains eight washers. These parts attach to the tank and are made out of metal. They are genuine items that are supplied by the original equipment manufacturer for use with Craftsman air compressors. During replacement, it may require a wrench to help install these parts correctly. They will require replacing if they become bent or broken.
It is a genuine manufacturer-approved replacement switch which is used with Craftsman power tools. This is the part of the tool handling on/off operations, it includes the safety key which prevent unauthorized use. Over time switches tend to wear away and may begin to fail eventually requiring replacement to maintain a properly working tool.