Is your vacuum not working as effectively as you want it to because your filter needs to be replaced? Our Kopach filter is just what you need. This filter will fit most Craftsman brand vacuums (1988 to present brand, 5 gallon and bigger sizes) and some Ridgid vacuums, but please be aware of the following specifications so you can make sure you have the parts you need: This filter will fit your Craftsman red-stripe filter (Part #9-17816) without any adapter parts. You can use our filter on a Craftsman vacuum if your current filter uses a filter cap and wingnut to secure the filter onto the filter cage. (If you need to replace the cap and wingnut, we also sell those!) Note that if your current filter attaches using rubber across one side that snaps over a ball, then our filter can work, but you will also need to order our Filter Adapter Kit. This filter will also fit some Ridgid brand vacuums. This filter will replace your Ridgid vacuum Part # VF4000 filter (which is open on both sides). If your current Ridgid filter has rubber across one side that snaps over a ball to secure it onto the vacuum, then our filter will NOT fit your vacuum. If this is the first time you are ordering a filter for your Ridgid vacuum, you will also need to buy our reversible cap and wingnut. If you insert the filter into the vacuum and the cap does not fit, try flipping it over to the other side. If you have any problems with the filter fitting your vacuum, please feel free to contact us and we would be happy to help. The dimensions of our filter are 8 1/8" high with an interior dimension of 4 3/8" and an outer dimension of 6 1/2". Please contact us through our Amazon home page if you have any questions. This product is manufactured by Kopach Filters, LLC. This product is not manufactured, sponsored, or endorsed by Craftsman or Ridgid. The Craftsman and Rigid names are registered trademarks.