The updated RP055 from ISC is a 3/4” capacity spring block perfect for the working arborist. This rigging block combines the convenience of spring loaded upper pin with a captive bushing, and a lightweight aluminum design. The rope friendly rounded side plates are thick aluminum with a blue powder coating to enhance the life of the block. It is tensile tested to 22, 500 lbs, with a safe working load of 4,496 lbs.