VENTED OR NON-VENTED Motorcycle Polished Aluminum Gas/Fuel Tank Cap Knurled - Steel Stepped Bung - Custom Harley Chopper Bobber Cafe Racer Billet aluminum cap and stepped steel bung easily welds to any steel tank. Knurled Cap - Machined from 6061 Billet Aluminum and polished to a mirror finish. Steel Bung - Machined from D.O.M steel and stepped to make welding a breeze. Just drill a 1-1/2" hole and drop it in. Thread Pitch= 1-1/4"-12 (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.