The Aeroflow Performance line of premium quality weld-in bungs is CNC machined from solid aluminum billet (6061), CS1030 steel or 316 Stainless Steel. These female NPT weld on fittings have a precision-machined taper to exact tolerances for trouble-free installation of NPT fittings. Applications include but are not limited to oil or fuel tanks, radiators, valve covers, manifolds and rear axle housings. Note: NPT threaded fittings should always be sealed with Aero seal Thread Sealant (AF98-2023) or similar PTFE thread sealant.