Provided with a release liner over the hydrogel. May be used with the release liner in place. Non-sterile, single patient use only. Will not collapse under patient's body weight, ensuring even distribution of water flow and temperature throughout all pads. Water flows through pads via negative pressure circulation, creating a leak-proof system. Not made with natural rubber latex, not made with metal, and radiolucent. 4 pads individually wrapped per case.