The SUN-PACK MOIST HEAT PACK is a clinical moist heat pack designed for professional use. The SUN-PAK is designed for use with the SUN-PAK N-1 Four pack heating unit or any comparable water immersion heater. These clinical quality hot packs come in three sizes to fit every body contour. Each SUN-PACK is designed to give up to 35 minutes of soothing, therapeutic moist heat and features convenient color coded tabs for easy handling.