Back Panel Wrap-Around Cord Design Lets you store cord when heater is not in use. Vertical Thermal Tunnels Are engineered to maximize radiant heat flow while maintaining a low surface temperature. Permanently Sealed Never needs refilling! Unit is permanently sealed with pure diathermic oil for stable and efficient heating. Patented Smart-Snap Wheels Convenient pre-mounted wheels ensure safety and stability of the unit. With their patented design, they snap into place perfectly - no assembly required!