Reusable Instant Heat Pack - Pad - Shoulder, Neck Joints and Muscles - One Snap Yellow - Only one reusable heat pack as shown in the first picture. All you need to do is flex the metal disc, and you activate a chemical reaction that heats the pad. This is safe to soothe body pains and aches. And it doesn?t use electricity so you can use it anytime, anywhere. In the office, on the train or in the great outdoors, this is ideal for men, women and children. When to use the Shoulder Neck Heat Pack: To soothe and relax the tension in your muscles. To relieve the soreness and swelling from injuries. To ease stiffness and increase mobility in joints. Instructions for Use: Click the metal snap to activate the heat and enjoy the warmth. To Reuse: Wrap the heat pad in a cloth (to prevent it from melting). Boil a pot of water large enough for the pad. Boil the heat pack in the water for approx 20 min. (until all crystals are liquid). Remove the pad from the water and allow it to cool. The pad is now ready for use.