60mm Quint Dynamic Block.Designed for use as a low friction mainsheet system on sports catamarans, but suitable for many other applications including backstay tensioning on keelboats.For a complete 10:1 mainsheet system, also look at A2169 - Pro-Ratchet 60mm Quint Block.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 Ð The A2069 comes with a removable swivel lock moulding. When installed, the shackle can be locked in 90-degree orientations. When removed, the attachment shackle can spin freely.Becket Ð A large central hole not only reduces the overall weight of the block but also offers a rope friendly attachment point.