The 8×12 is great for any part of your back. It covers a wide area and it can also be used to wrap around sore joints and muscles. The 8×12 last about two hours depending on how well you insulate it. You can also use the heat pack as a cold pack. Just place it in the freezer for up to one hour and it will stay soft and flexible.
Part Number: 812H
8x12 Heat pack "HotShotz" Lower back (20.3X30.4cm)