1[ABS Material and Auto Constant Temperature] Mini aquarium heater is made of safe ABS, which is ,safe and non toxic, not harmful to pets' health. Automatic constant temperature design, the heating can be stopped when the set temperature is reached, preventing overheating from causing damage to pets.2[Applicable Power] 20 room temperature standard as a reference. When the room temperature is 20, 50W of 15L of water is enough, but if the room temperature is below 15 , more power must be used. It is also necessary to consider the heat dissipation conditions, whether the sealing of the fish tank is good, etc. It is recommended to choose a large power.3[Note] Around 26C constant temperature, the temperature cannot be adjusted. If the room or water temperature is 26C, it will not work. Human body temperature is around 36C, not suitable to test whether jeater is working or not. It is recommended to use a thermometer. The normal water temperature is 2227 C, that is, the heating rod is working.4[Easy To Use] Aquarium heating rod is easy to use, plug to work, built in automatic thermostat sensor chip, complete automatic control, only need to be completely submerged underwater, automatic control of water temperature to maintain at about 26 . (the best water temperature for fish and turtles is 24 26 )5[Water Temperature] In actual use, the temperature will vary depending on the size of the body of water presented water temperature are different, test small bodies of water temperature will be 30 , large bodies of water may be under 20 . Heater has 2 suction cups on the back which allow it to be mounted horizontally or vertically in your tank.