180-degree push-on hose end in AN4 (-4), pushing straight onto socketless hose and gripping the barb without a clamp or crimped socket. AN4 is the smallest size in the range, so it lands on gauge and sender feeds, vacuum and boost reference runs, small breathers and low-volume returns. The 180-degree body sends hose straight back alongside itself, replacing a hand-formed U-bend that would otherwise kink or crowd nearby components. It moves very little volume by design, so keep it off anything that has to shift fuel or oil in quantity. Match the hose to the fluid you are running and seat it fully before pressurising the line.