PROPERTIES · UV resistant Acetal disc · The HL blocks have a Nylatron® disc that can be used for wire or rope · Fiber reinforced and UV resistant nylon block · Double ball bearing system runs on a polished stainless rail and acetal base, providing minimum weight and great strength · 316 stainless steel swivel · The cleaning holes for the ball bearings make it easy to rinse salt and sand out of the balls with fresh water to ensure a long and functionally safe lifetime of the blocks.