Overview of Dry Ice
Dry Ice is frozen Carbon Dioxide. Dry Ice is particularly useful for freezing, due to its low temperature: -109.3°F or -78.5°C, Dry Ice changes directly from a solid to a gas -sublimation- in normal atmospheric conditions without going through a wet liquid stage. Therefore it gets the name "dry ice".
Dry Ice will save all your frozen goods. Commercial shippers of perishables often use dry ice even for non-frozen goods. Dry ice gives more than twice the cooling energy per pound of weight and three times the cooling energy per volume than regular water ice (H20). It is often mixed with regular ice to save shipping weight and extend the cooling energy of water ice.