3M™ Nickel Cadmium Battery Pack GVP-111 supplies the power to operate the motor blower of a powered air purifying respirator system. The nickel cadmium battery has overcharge protection, provides up to eight hours of use per charge and has a life of approximately 1000 charge/discharge cycles. Powered Air Purifying Respirators are motorized systems powered by a battery pack which draw air through a filter or cartridge to provide respiratory protection to the wearer. The blower unit can be mounted on the waist, face, or head, depending on the system selected.