Professional quality unavailable in stores. ActiveWrap's unique non-migrating gel packs deliver the smoothest heat and ice treatment on the market today. These thermal packs are unexpectedly soft and flexible. Use in microwave, hot water or the freezer to give you total versatility of use. Elastic stretchy gel alleviates bare spots for a uniform treatment. This 7 x10 inch large size is for use with the ActiveWrap Shoulder, Knee and Back models.