Tests to greater strengths than other pulleys in the same range of size and price. It has the required prusik minding capability for use in 3-to-1 Z-systems (which means it makes it easier to haul up heavy stuff without popping a vein, or to lower heavy stuff without dropping it!). A smooth running 1.25'' nylon sheave runs on a zinc-coated axle, and the color-contrasting aluminum sideplates rotate for easy rope insertion and removal.