The Allen 30mm High Load Dynamic Block with SA.873 Key is designed for use as the ILCA top Vang block. It features a heavy-duty stainless-steel sheave for faster rolling speeds, higher working loads, and lower friction. The block has a removable clevis pin for easy attachment and uses a patented bearing system with twin rows of stainless-steel ball bearings for superior load-carrying ability and longevity. The central rivet on the 20 & 30mm blocks reduce weight and provide a rope-friendly attachment, making it ideal as a tie-off point in cascade systems.