I bought a couple of these Geni heat packs for keeping young animals warm during a rescue. I can't stop playing with them! I wish it didn't take so long to reset the sodium acetate. I've discovered that if you wait until the reaction is finished after you pop the disc then vigorously scoosh them between your hands to break up the crystal, the heat given off by the reaction is almost to much to touch. I'll have to wrap them in soft cloth so the babies don't get burned.