A SUS303 stainless inverted seat adapter taking an AN3 line onto an M10x1.5 metric thread, the coarsest of the three common M10 pitches. The inverted seat allows the factory brake pipe flare to bed against a female cone and seal properly; substituting an AN male flare here produces a joint that leaks however hard it is tightened. On the AN3 side, a standard braided hose connects, so the original hard lines stay as they are. SUS303 stainless gives the corrosion resistance this position needs, sitting in the path of brake fluid, water and road salt. Because M10x1.0, x1.25 and x1.5 all engage far enough to feel correct at first, gauge the port before ordering. Bleed the system thoroughly and check the joint under sustained pedal pressure before road use.