Use your H.E.A.T. app to connect and control your H.E.A.T. One-Layer suit. Controlling the top and bottom separately, the app gives you the ability to control your heat ranges from Low to Medium to High. The app also gives you a battery fuel gauge for each garment so you can stay on top of your battery life and not worry about getting stuck out in the cold with out your H.E.A.T.