These Big Block Chevy fabricated aluminum valve covers come with pvc port holes on each cover and a fill bung with billet cap on the front of one cover. The valve covers are designed to be light weight, yet strong enough to prevent warpage. They are constructed from .100" aluminum, with heavy wall mounting tubes and are welded while mounted on cylinder heads to ensure a proper fit. Additional fill bungs, AN fittings, or breather stacks can be installed on a special order basis. Stainless socket head mounting bolts included.