2 Variable Speed: Reduce water Temperature and Drop up to 2 ~ 5℃（Depends on Weather and Indoor Temperature） Wall-Mounted: Adjustable Jaws can Clamp the tank wall that thickness within 1.2 cm Rated Voltage: 12V safe voltage,with high security standards and ensure the safety of the fan Physical Cooling: Offer a couple degrees cooling to offset lights and UV filter Tips; When using Aquarium Cooling Fan, the water in the Fish Tank will Evaporate over time, Please Increase water in time fish tank cooling fan