IBF HSFG 8.8S Bolt set M20x65 (Bolt set includes one nut and one DTI washer)

HSFG bolts are High Strength structural bolts which have been tightened such as to induce predefined tension in the bolt shank. Due to the tension in the bolt, the interface between the plies (steel members in a joint) cannot move relative to each other because of the frictional resistance. The bolts act differently than normal bolts or rivets. They work on Friction Grip mechanism where load is transferred through frictional resistance between the plies.