1.best quality for 3"~26" 2.ISO&API 3.high quality, best price 4.cover all IADC code 1 Specifications: Size8 1/2”(215.9MM)IADC517Bearing ... ”),155.5mm(6 1/8”),158.7mm(6 1/4”),161.9mm(6 3/8”),165.1mm(6 1/2”)190.5mm(7 1/2”),193.6mm ... (7 7/8”)212.7mm(8 3/8”),215.9mm(8 1/2”),222.2mm8 3/4”) 241.3(9 1/2”),244.4(9 5/8 ... /8”),349.2(13 3/4”)374.6(14 3/4”)381(15”),393.7(15 1/2”),406.4(16”)444.5(17 1/2”),508 ...