The 100761306 Flange Bolt Set is designed for joining a size NW63 ISO-BF bolted flange to a size NW63 tapped flange. This set of 304 stainless steel hardware includes (4) M8 threaded 40 mm bolts with 1.25 mm pitch and (4) 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.