These portable power supplies are an excellent way to power your avionics on the ground while you train or practice in the cockpit. Especially helpful in learning how to operate glass cockpit avionics and panel mount GPS units. To use the Portable Power Supply plug the cord into an AC wall outlet, and then connect the 3-pin plug into the external power receptacle on your aircraft. Furnished with Cessna style 3-pin plug. Manufactured in U.S.A. This unit can also be used as a battery charger, by using the battery clip adapter which is provided with the unit.