Two small units. Equipped with integrated rechargeable Lithium-ion polymer batteries. (1) USB wall charger and (2) USB cords. Charges in 4 hours or less. Thin and lightweight. Easily turn off at the touch of a button. Up to 6 hours of constant heat per charge. Three temperature settings reaching up to 116 degrees. Recharges over 500 times. Shock and water resistant. Hang packaged.