The Allen 20mm Dynamic Block High Load Back To Back features sheaves facing opposite directions, allowing for control lines to run 180 degrees to each other. It has a strong stainless steel side strap and nylon mouldings to prevent separation under high loads. Its design is also suitable for use in triangle backstay systems and dual pole and spinnaker launcher systems. This high load sheave has a stainless steel sheave with a slight V shape profile that can be paired with both wire and Dyneema. It also has a patented bearing system and a large central rivet for a rope-friendly attachment. Each of these features contributes to reduced friction, higher working loads, better performance, and durability compared to other blocks.