The UST Reusable Hand Warmer is a temporary warming tool for when you need an extra heat source whether you're at home or out in the elements. It is environmentally friendly and can be used again and again, so say goodbye to the one-use disposable things you've been using before. Features: Heats up to 54° C in just 15 seconds Provides heat for up to 2 hours Environmentally friendly Sodium acetate and water are activated by bending a metal disk inside the pouch When heat runs out, warmer can be rejuvenated with boiling water How to use: Press metal button on the disc hand warmer until it clicks, and liquid starts to crystallize Massage hand warmer until completely crystallized Apply hand warmer to desired area Insulate hand warmer in a towel or cloth material for longer lasting heat How to recharge: Bring pot of water to a rolling boil, then lower heat to a slow simmer Carefully place hand warmer in simmering water Keep hand warmer in simmering water until crystals completely dissolve & liquid turns clear (approx. 15 minutes) Carefully remove hand warmer and allow to cool to room temperature before use If heat pack re-crystalizes after boiling, re-boil until crystals completely dissolve Warning: CAUTION: DO NOT MICROWAVE Contents hot after boiling/recharging Allow to cool to room temperature before handling or reactivating Do not puncture or open pouch Do not ingest liquid contents Avoid freezing