The Hydor Hydrokable Heating Cable is a versatile substrate heater designed for use in aquariums and terrariums. Ideal for use completely submerged or in a dry habitat. The Hydrokable provides regular and even heating throughout the substrate media. In the aquarium, the warmed water creates a slow water circulation effect throughout the media, which is beneficial to many varieties of live aquatic plants and other aquarium inhabitants. The Hydrokable is best used with the Hydor Hydroset for precise temperature control. Use of the Hydroset allows the Hydrokable to be used to stimulate specific plant growth cycles as well as to meet specific reptile heating requirements. For ideal plant growth conditions, use the Hydroset to maintain the substrate temperature slightly higher than the aquarium water temperature. While the use of the Hydroset is recommended, the Hydrokable functions properly on its own and will heat the substrate accordingly in relation to the suggested gallons noted in the instructions. The Hydroset is intended to be used in an ‘S’ pattern using the included suction cups.