These packs use a unique combination of pressure point therapy and cold therapy to help relieve headaches and pain. Linked therapy balls, encased in a cold therapy gel, are ergonomically positioned to fit pressure points at the base of the skull or lower back. Gentle pressure is applied when the pack is pressed between the body and a chair or mattress. The packs can be used at room temperature or cooled to help with headaches. Cold therapy constricts blood vessels, resulting in decreased blood flow to the area of application. That helps to decrease swelling and promote healing. The Dual Comfort cover for the packs offers both slow-release and rapid-release treatment surfaces. The cold gel is non-toxic and biodegradable. Store the packs in the freezer for convenience. Size