Ronstan's Series 20 Ball Bearing Utility Blocks are a range of lightweight blocks with high static and dynamic load capacities and versatile head fittings. They feature precision-moulded, UV-stabilised acetal sheaves running on stainless steel ball bearings to give high performance and low friction. They are ideal for Dinghy control lines and vangs, cunninghams and traveller controls. Can be fitted with a shackle in either of two planes to allow correct alignment of the block.