The swing-side aluminium has plates that swing open to install rope. Particularly useful for use when doubling the line, the rope cannot accidentally come out of the block. Use the steel locking carabiners or shackles to anchor to a polyester sling. The 63 mm (2-1/2'') diameter aluminium pulley is mounted on self-lubricating bushing and stainless steel axle. The swing sides are also made of anodized aluminium.