Billet Proof Designs Polished Aluminum Gas Cap. All you need to do is weld it in and fill it up! Easily welds to any 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 1-1/2" 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! Dimensions: Cap ONLY: OD= 1 5/8" Height (Including Threads)= 3/4" Knurled Edge= 1/4" Bung ONLY: OD= 1 5/8" Height= 3/8” Thread Pitch= 1-1/4"-12 Finish: Polished Aluminum. Included: Billet Aluminum Cap, Buna-N Seal, ALUMINUM Bung. Fitment: Will fit in any ALUMINUM tank that is able to accommodate the above dimensions. *Also available in solid brass!*