The Hot/Cold Water Bag is a simple, yet effective tool to relieve sore muscles, soothe minor muscle pain and cramping, and alleviates stress and tension. This thin, lightweight, sturdy bag can support up to 600 lbs of pressure. It is designed to deliver heat or cold therapy to any part of the body quickly and easily by conforming to all body curves. Hypoallergenic, No Latex, No Odor. It comes in three sizes: Large (5 Gallon), Medium (2.5 Gallon), Small (1 Gallon).