Straight 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. Use the straight body wherever the hose can run in line with the port, since it adds the least length and the fewest turns to the circuit. It moves very little volume by design, so keep it off anything that has to shift fuel or oil in quantity. Fit it to hose made for push-on use and seat the hose fully against the fitting shoulder.