An adapter carrying an AN6 male 37° flare at one end and a larger Ø12 hose barb at the other. The bigger barb suits the thicker rubber hose used on tank breathers, vent lines, overflow and catch-can plumbing, coolant bleed runs and low-pressure returns, letting those sections stay in inexpensive rubber while the rest of the circuit runs AN. It is also handy for joining an AN6 line into an existing OE hose of that size without recutting the whole run. The barb end is clamp-sealed and belongs on low-pressure duty only; the flare end seals metal to metal and takes no sealant. Choose hose properly matched to the Ø12 barb — over-stretched hose relaxes and weeps — and clamp behind the barb ridge with a suitable fuel-rated clamp.