Shoulder Bolt Hardware. Includes one set of Dimebag 1" mounting hardware (8 bolts and 8 lock nuts). Made of high-grade steel and have reduced, rounded heads and counter sunk for less board stress. The top part that is inside the wood and truck holes (shoulder) is not threaded, so the bolt fits snugly and has less vibration, which keeps the nuts from loosening and makes the bolts and the board last longer. Keep your board looking fresh and keep those trucks locked on tight with Dimebag Hardware!