Basic building blocks of most rescue systems. Feature precision sealed ball bearings to minimize loss of mechanical advantage. Large carabiner hole supports multiple carabiners, and the smooth, rounded edges on the high-strength aluminum side plates minimize rope fraying. Bottom is shaped for maximum efficiency with Prusik hitches but also works well with Gibbs-type ascenders. Large anodized aluminum sheaves provide efficiency, and low-profile axle fasteners reduce snags when the pulley is moving.