50mm Single Dynamic Block.The A2050 is a high performing ball bearing block, designed to eliminate friction and allow rope to run at great speeds. Ideal for use on Keelboats and Catamarans for a range of applications from jib sheet to mainsheet systems and everything in between.Bearings Ð Dynamic Blocks feature our patented bearing system which uses twin rows of stainless-steel ball bearings running on a stainless-steel rail. This provides a superior load-carrying ability and longevity when compared to other bearing systems available on the market.Swivel Lock - The single block features a swivel lock, located at the head of the block. Simply turn the locking screw to either lock the swivel in 90-degree orientations or unlock it for a complete free spinning shackle. Becket Ð A large central hole not only reduces the overall weight of the block but also offers a rope friendly attachment, perfect as a tie-off point when being used in a cascade system.