The Allstar Performance Countersunk Bolt Kit, featuring a 1/4-20 inch thread and 1 inch long Allen head bolts, is designed for a seamless, flush finish on various surfaces. With 1 inch outer diameter countersunk washers and nyloc nuts, this aluminum and steel kit ensures a smooth, aerodynamic surface, ideal for mounting roofs, side skirts, and spoilers, or replacing sharp edged fasteners inside cockpits. Set of 10, in a natural finish, guarantees durability and style for your fastener needs.