1.250-12 unjf 3b rh thread, steel 303 astm a582, passivate qq-p-35, 1.990 in. Min and 2.010 in. Max od, 1.075 in. Min and 1.095 in. Max nut height, 6 equally spaced locking splines, 0.427 in. Min and 0.447 in. Max spline depth, minus 65 degrees f to 450 degrees f max temp rating