These versatile heating pads can be used cold from the freezer for injuries, or hot from the microwave for aches and pains. Microwave your heating pad straight from the freezer for therapeutic moist heat! Great for aches and pains of the neck, back, knees, and joints. Safer than corded heating pads because there are no cords to trip over. Heat slowly dissipates so no chance of overheating. Made with soft 100% cotton. Unscented. Measures: 21.5" L 8" W Directions & freezer bag included with each pack. Four chambers filled with whole corn (not popping corn) since corn holds both heat and cold the longest of all natural grains used as heating pad fill, as well as being the most comfortable for contouring to your body and staying put. NOTE: Chambers are purposely not completely filled in order for the pack to be able to mold to your body.