Authentic OKMO valve (not "GV-A2 style" Alibaba junk). That 1/4x40 TPI?. We cut it to match 1912 Loco Maintenance Co. gauges down to the flank angle. Bore's laser-mic'ed at 3.5mm - tight enough to strangle a Case 65's steam curve but loose enough to feed a hungry 3" Shay.
