The re-usable Hot Button hot pack instantly becomes hot once the button inside the pack is activated. The pack remains hot for at least 30 minutes. Re-usable pack is "recharged" and made ready for a future activation by boiling it for approximately 10 minutes. The activation and recharging of a pad can be repeated at least 100 times. The Hot Button contents are not harmful; they are common non-toxic food additives. Activate pad by gently flexing disk within the pad back and forth until pad starts to crystalize; pad will heat to approximately 130°F (54°C). For cold pack refrigerate do not freeze. To return to liquid state wrap pad in cloth, place in boiling water for 5 to 12 minutes.