Wood's PowrGrip makes these vacuum lifters very easy to use. These units are equipped with an onboard battery operated vacuum pump and battery charger. After the vacuum pads are placed on a clean surface, the operator turns the onboard vacuum pump on. When a safe lifting vacuum is reached the pump automatic shuts off. The operator can now lift, tilt and rotate the panel or unit for positioning on the building. When the panel is securely in place the man on the lift turns the unit off. It takes a few seconds for the lifter to let go and you are ready to retrieve the next panel. If any unexpected vacuum lose occurs the pump automatically turns on and pumps down to a safe lifting level and shuts back off. Used correctly, with a fully charged battery the lifter will do about 100 lifts.