The ISC Double Progress Capture Pulley's are designed for lifting or hauling. Supplied in two versions these progress capture pulleys come equipped with bushed alloy sheaves and locking cams. The ISC Progress Capture Pulley non-locking version has standard free running wheels. The sheave of the locking version runs freely in one direction for minimum friction when lifting or hauling. In the opposite direction, the sheave is locked to provide maximum friction when lowering. These progress capture pulleys are ideal for hauling and rescue and with the addition of an extra pulley can be used to create a mechanical advantage system.