The hand warmer contains a super saturated solution of water and sodium acetate. Snapping the metal disc creates a chain reaction causing the solution to crystallize, giving off heat. The heat packs can be recharged back to the liquid state by boiling water for 10-15 minutes and allowed to slowly cool. 4 x 4 inches.
100% Satisfaction Guarantee: At Mansion Schools, we want to be sure that the item you choose is the right one for you. Within 30 days of delivery of your order, you may return any merchandise purchased from Mansion Schools in its original condition with your email order confirmation or packing slip. Restocking fees may apply. On items over $275 shipping within the US, we will even arrange free pick up or pay for returns shipping.