This heater combines advanced streamlined design with water-calibrated. VisiTherm accuracy and performance assurance. It delivers the ultimate in easy-set adjustability, shatterproof durability and efficient overheat-protected operation. Start up is easy--just set it, install it and plug it in. Good for freshwater or saltwater aquariums. Other features include: UL listed; red temp select dial on top of heater; has an aluminum cylinder and eight-cavity heating element to distribute core heat evenly, efficiently. use on aquariums up to 10 gals.