The 100761206 Flange Bolt and Nut Set is designed for joining two size NW63 ISO-BF bolted flanges. This set of 304 stainless steel hardware includes (4) M8 threaded 40 mm bolts with 1.25 mm pitch, (4) M8 nuts, and (8) M8 washers which is what is required to join NW63 vacuum flanges. Series 76 ISO-BF flanges and seals are designed to be tightened to metal to metal contact. It is important that the bolts not be over tightened or warping of the flanges could result. The torque rating for flange bolts is 7 to 10 pounds per foot.