20mm Triple Dynamic Block With Becket.Our Dynamic range is generally the best choice for applications that require constant sheave movement.Becket - This block has a becket to make tieing off easier. The becket also helps keep the load central. 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 which run on a plastic rail.Ultra-Strap Ð Our patented Ultra-Strap is used in our 20, 30 & 40mm Dynamic blocks. The Ultra-Strap is unique when compared to other designs because of its coining process. This process strengthens the strap, making it more reliable and hard-wearing as well as making it much more rope friendly than other designs. The Ultra-Strap was the first marine industry block designed to work specifically with a rope attachment.