1. Fits Jesse James Chopper Tanks, West Coast Choppers tanks and many other aftermarket Chopper Tanks 2. Vented cap 3. Made from 6061-T6 Billet Aluminum & hard ABS plastic 4. Diameter of top: 1-5/8" 5. Diameter of threads (bottom plastic piece): 1-3/8" 6. Length/Height: 2"