This unique device is a double pulley combined with a camming device. The 3″ sheave diameter increases mechanical efficiency and the color coding of the swing side plates make rigging simple. Cam may be locked open or retracted for quick remote release by the attached cord. The cam comes with a lifetime guarantee, if the cam wears out we will repair or replace it. Use it to rig 3:1, 4:1 mechanical advantage systems as needed. Made in the U.S.A.