The extended-body steel AN16 weld bung. The longer body is the reason to choose it: on thick steel tank walls, boxed chassis sections or recessed panels, a standard bung ends up buried and leaves no room to swing a spanner on an AN16 hose end, which is a substantial fitting. The extra length also keeps the 37-degree flare seat away from the weld pool, helping the sealing face stay flat. AN16 handles coolant and header tank plumbing, breather and vent runs, dry sump reservoir lines and large transfers. MIG or TIG weld all the way around into mild steel and shield the thread from spatter.