Pro-Guard D2 Oil Filter by aFe. aFe created the Pro Guard D2 Oil Filter to handle the extreme conditions typically encountered by a heavy-duty diesel truck. Inside it has a synthetic composite material for maximum engine protection with minimal flow restriction. A 600 lb. burst strength canister guards the outside and a welded on 1in outside, 3/8in inside nut/ratchet drive fitting ensures that the filter is easy to remove come maintenance time.