... 1/2”)190.5mm(7 1/2”),193.6mm(7 5/8”),200.0mm(7 7/8”)212.7mm(8 3/8”),215.9mm(8 1/2”),222.2mm8 ... 1/2”),244.4(9 5/8”),250.8(9 7/8”)269.8(10 5/8”),295.3(11 5/8”)311.1(12 1/4”),346 ... .0 (13 5/8”),349.2(13 3/4”)374.6(14 3/4”)381(15”),393.7(15 1/2”),406 ... drilling information of the layer.4)plz tell the quantity. 8 1/2 215.9mm iadc 517 oil field drill bit