40mm Dynamic & 30mm Dynamic Linked Single Blocks.New for 2023.Made from high-strength, lightweight glass-loaded nylon and featuring AllenÕs dynamic bearing technology for a high-performance block suitable for keelboats and dinghies.40mm dynamic blocks are perfect for use on main, jib and spinnaker sheets on dinghies and keelboat control lines.Bearings Ð Dynamic blocks feature our patented bearing system which uses twin rows of stainless-steel ball bearings running on a stainless-steel rail. The ball bearings are caged for further friction reduction. These features provide a superior load-carrying ability and longevity when compared to other bearing systems.Linked - A great choice for mainsheet systems which require a traveller block (30mm) and a mainsheet block (40mm) attached as closely together as possible. Linking the blocks results in a limited chance of snagging or failure. The linked blocks can also be used in spinnaker and pole launcher systems. Becket - The 40mm range features a large central hole, which can be used as a becket (tying-off point).Please note - Max working load rated to A2030 block.