VENTED or NON-VENTED Motorcycle Polished Aluminum Gas/Fuel Tank Cap - ALUMINUM Stepped Bung FOR ALUMINUM TANKS ONLY - Harley Chopper Bobber Cafe Racer Billet aluminum cap easily welds to an ALUMINUM tank. Knurled Cap - Machined from 6061 Billet Aluminum and polished to a mirror finish. ALUMINUM Bung - Machined from 6061 Billet ALUMINUM and stepped to make welding a breeze. Just drill a 1" hole and drop it in. (2) 1/8" Buna-N O-Rings - ONE VENTED and ONE NON-VENTED INCLUDED - Temperature range -35 to +250 F. Durometer hardness is A70. Made in the USA using domestic materials.