AN3 is the small-bore size used for hydraulic brake and clutch lines and for instrument and gauge feeds, and this straight bulkhead union lets those lines cross a bulkhead, firewall or chassis rail without chafing on a bare hole edge. The extended shank drops through the panel and is retained by a bulkhead nut, leaving a male 37° flare on each face for standard AN3 female hose ends. It is a neat way to split a long brake run into serviceable sections so a single hose can be replaced without stripping the whole system. Bulkhead nut is a separate item. Fit against a flat, deburred surface for a square seat.