ISTA Aquarium Energy Saving Arrayed Cooling Fan ColdWind for fish tank Easy to install - no tools needed. Powerful cooling fans increase air movement to reduce heat and humidity. Large cooling fans provide powerful ventilation to reduce heat transference from aquarium equipment AC100~240V 50/60 Hz universal voltage Note: Clamp mounting bracket can fit over aquarium walls up to 1/2" thick. Please make sure the thickness of your aquarium wall (or the width of the lip around the top edge of your aquarium) is less than 1/2 inch.