"PART NO. AND RECORDED SERIAL NO. PERMANENTLY MARKED ON EITHER RING IN ACCORDANCE WITH SIKORSKY SPEC SFEAT1S8770. BORE AND OD TO BE COPPER PLATED 0.0001 TO 0.0003 IN. THK PER AMS 2418. INITIAL CONTACT ANGLE 45 DEG. OUTER RING CURVATURE 52 PERCENT,INNER RING CURVATURE 51 1/2 PERCENT. ALL CORNERS STONED AND POLISHED TO BLEND WITH BORE AND OD. ALL EXTERNAL CORNERS ROUNDED 0.0300 IN. MAX"