The Allen 20mm Tie-On Double Dynamic Block High-Load boasts a stainless-steel head loop for maximum strength and reliability. It also maintains proper orientation during use, preventing cheek separation with the use of a soft shackle. When fitting this block, be sure to follow the correct attachment method for optimal strength and stability. For further fitting advice, please contact us. The large central rivet and patented bearing system with twin rows of stainless-steel ball bearings make for a lightweight yet durable block with smooth rolling speeds and high working loads. Upgrade to our high load blocks for an even better performance.