"BORE SURFACE 63 MICROINCHES RMS FLANGE PERIPHERY, ID OF COUNTERBORE FLANGE AND HUB ENDS 125 MICROINCHES RMS; THIS HALF COUPLING IS FALK GRIDSPRING TYPE; KEYING FACILITY QTY:1; THREAD PROVISION:UNTHREADED; DISTANCE FROM CENTER OF BORE TO BOTTOM OF KEYWA:3.891"" NOM.; KEYWAY WD:0.998"" MIN.,1.000"" MAX.; COUNTERBORE DEP.:1.0625"" NOM.; COUNTERBORE DIA.:7.875"" NOM."