Eliminating screws and rivets, these unibody blocks are precision machined from a solid piece of stainless or aluminum, folded in half and then assembled using non-conductive Delrin on all mating surfaces. Every block now has built-in adjustment that allows the shackle to swivel or lock with a simple set screw. Effortless rotation is assured with Torlon ball bearing construction High strength, low weight Corrosion resistant