The Kopach Wingnut is designed to fit both Craftsman and Ridgid vacuums, for Craftsman this wingnut is a replacement and will work with filters designed to fit onto Craftsman shop vacs. For Ridgid, this wingnut is required one-time purchase (along with the cap) to make Kopach Filters fit onto Ridgid shop vacs. If you have any problems with this wingnut fitting in your vacuum please feel free to contact us and we can help you get what you need!