The Aqueon Pro 200 is a precision calibrated adjustable aquarium heater with a sleek and slender design able to service both freshwater and saltwater tanks of all different types and sizes. This unit comes with a unique safety feature as well, where if the top of the heater sinks below the bottom of the heater, it will turn itself off automatically. Combined with temperature adjustment accuracy within +/- 1F, this gives users the ability to control every aspect of their aquariums. One of the more celebrated features of this heater is it's shatterproof design and sturdiness. Constructed of a solid metal core encased in a thermal plastic housing, this heater is built tough and built to last. 3.5 x 1.5 x 12.875