A stainless inverted seat adapter taking an AN4 line to an M10x1.0 metric port. M10x1.0 is among the most widely used metric brake threads, and the inverted seat on this adapter is what lets the factory pipe flare bed correctly against a female cone — an ordinary AN male flare in the same port simply will not seal, regardless of torque. The AN4 side accepts a braided AN4 hose, making this the part for builds running the larger line size onto a metric system without re-flaring or replacing the original pipework. Stainless construction handles brake fluid and road corrosion in an exposed position. Confirm the pitch with a gauge, as M10 also exists in 1.25 and 1.5. Bleed thoroughly after fitting and check the joint under held pedal pressure.