The Allen A2020 Dynamic Block with Swivel Hook is a lightweight and durable pulley specifically designed for use with smaller diameter lines in applications such as dinghies, windsurfing, and kitesurfing. With its patented twin row stainless-steel ball bearings and central rivet design, this block offers superior load-carrying ability and longevity compared to other bearing systems. The built-in swivelling hook allows for easy attachment and swiveling to align with changing pulling forces, providing added versatility. Note that the swivel cannot be locked.