Hand Boilers are looped in the twisted glass sculptures containing a liquid that will "boil" as heat is transferred from your bare hand. Simply hold the large bulb end on the bottom in the palm of your hand and within minutes, your body heat from your hand will cause the liquid to rise. Once out of your hands, it takes a few minutes for the liquid to cool down. Pretty fascinating science toy and an excellent demonstration of energy transfer. The amazing balance bird will balance on most anything. balance on your finger, a television, or make your own unique stand! The balance bird helps teach the principles of gravity and center mass and makes a unique and interesting display. One Hand Boiler and One Balances Bird. Additional Details ------------------------------ Product description: Hand Boilers are looped in the twisted glass sculptures containing a liquid that will "boil" as heat is transferred from your bare hand. Simply hold the large bulb end on the bottom in the palm of your hand and within minutes, your body heat from your hand will cause the liquid to rise. Once out of your hands, it takes a few minutes for the liquid to cool down. Pretty fascinating science toy and an excellent demonstration of energy transfer. The amazing balance bird will balance on most anything. balance on your finger, a television, or make your own unique stand! The balance bird helps teach the principles of gravity and center mass and makes a unique and interesting display. One Hand Boiler and One Balances Bird.