Based on Russ Anderson’s original design–that are legendary throughout the fire, rescue and work-related professions.– these pulleys are essential equipment for the serious rigger. The SMC/RA 4″ Double Stainless Steel Pulley rotating side plates allow attachment of the pulley anywhere on the rope and will accept multiple carabiners. Axle nuts are marked with a blue witness line to indicate if the axle nut has been turned or tampered with.