... 15/16Connection Screw ThreadConnect to Center Pipe APIREG 4 1/2,LHREG 6 5/8,LHREG 7 5/8,LHREG 4 ... 1/2,LHConnect to Kelly APIREG 6 5/8,LHREG 6 5 ... for drilling,SL135 SL225 SL450 SL585,exchanged with HH,BOMCO,LS-NOW,factory Price,Free logo printed