An AN4 straight bulkhead union for smaller-bore lines — brake and clutch circuits, turbo oil feeds, gauge and vacuum sender plumbing and boost reference lines. It mounts through a drilled panel on its extended threaded shank and is locked with a bulkhead nut, so the line terminates either side of the panel rather than running through it. Both faces are male 37° flares accepting any standard AN4 female hose end, swivel or adapter. Useful on turbo oil feeds in particular, where a bulkhead point at the bay wall keeps a hot line clear of moving parts and makes later servicing straightforward. Bulkhead nut supplied separately.