The Phase 22 Shipping pack act as a temperature sink to provide temperature stability when shipping reptiles, amphibians, and plants. These special shipping pack want to always be at 22° C. Phase 22 shipping packs are specially designed to automatically go through two phases, a “warm” phase, and a “cool” phase, depending on the ambient temperature around them. When used properly they will help maintain your package and its contents at a steady 22° C. When temperatures drop below 72° F (22° C) a chemical reaction turns the Phase 22 packs material into a liquid that slowly releases a steady warmth. When the temperature rises above 72° F the pack solidifies and releases a steady cool temperature to help protect your package contents. Provides thermal protection when shipping products between 15-30°C When used as liquid, keeps contents warm When used as solid, protects contents from heat We recommended that you use a minimum of 2 packs per box when shipping live animals.