Provide up to 12 hours of safe, comforting warmth for your pet without worrying about electric wire or controls. Snuggle Safe's interior, ThermapolTM undergoes a physical change of state during the heat cycle. While other products would be getting cooler, Snuggle Safe actually generates extra heat as the ThermapolTM changes. This process lasts for around 5-6 hours. During this time the temperature remains stable at around 123F. It gives extended warmth unmatched by any other non-electric heater. Simply put it in your microwave for 5 minutes and then put under your pets bedding.