CMI® Knot Passing Pulley is arguably the best of its kind. This small pulley is made of stainless steel and has the highest strength to weight ratio of any pulley in its class. Extra wide 3" aluminum sheave easily passes knots in 1/2" rope. It consists of a large pulley rigging hole that accepts up to 3 carabiners, and the two smaller holes are for pulley tagline attachment.