If you're replacing the piston/cylinder seal in your nailer, chances are this valve seat is at or nearing the end of its life - they're made from the same material. This seal is proven to fit and perform in Central Pneumatic (Harbor Freight) 98751 3-in-1 nailer and may fit similar model nail guns. I've listed rough sizes in the product details and they're shown in the pictures. If you have any doubts, measure yours first! If you have something that's different than this, message me. I can duplicate it and create a listing for you. Check out my other listings for other models. Thanks for looking! framing nailer nail gun 18 21 28 30 degree repair gasket diy wood woodworking compressed air Wen Northern Paslode Craftsman Kobalt Metabo Milwaukee DeWalt Rigid Numaxx Makita Dotool Valu-air Stanley Ace Menards Lowes Home Depot Husky deck home construction remodel tools carpentry contractor industrial DIY woodworking concrete cement masonry framing roofing finish finishing brad trim