This 5 in x 9 in Portable Warmer from HotShotz is a multipurpose heat pack. It can be used just about anywhere for any part of the body. The heat pack is actually large enough for use on the neck, legs, arms, and even your lower back. Also, convenient for on the go travel. Great for keeping warm whilst out and about or to relieve pain on the go or at home. It is good for those who suffer from sore, achy muscles and cramps. Also, great for using if you suffer from coldness from Raynaud’s, anemia, thyroid problems, or iron deficiency. To use the HotShotz Portable Warmer, squeeze the activator button until it clicks and the warmer will automatically heat up on its own and be ready to be used. To recharge after first and each use thereafter, wrap with a fabric cloth (dish cloth, for example), place and leave the heat pack in a pot of boiling water for 10 to 20 minutes, making sure all crystals have melted. Take it out of the pot and let the warmer cool down to room temperature and it’s ready to be used! Usability will generally last an hour. Time will change depending on how you use it and how well you insulate it. Don’t forget to look at the accessory Arm Strap, sold separately, which is made to hold this size warmer right where you want the heat.