Choose the Allen 20mm Allenite Through Deck for smooth rope and wire control line guidance, designed with a durable acetal body that houses the sheave for reliable performance in adjustable rigging and other high-load situations. Available with one or two sheaves, and in plain and ball-bearing systems, these blocks are suitable for a wide range of applications. Our patented bearing system features twin rows of stainless-steel ball bearings on a stainless-steel rail, ensuring superior load-carrying capacity and longevity compared to other plastic rail systems.