This is a vacuum UV Lamp--Replacement UV Light Tube, which emits germicidal shortwave UVC with a peak at 253.7nm wavelength to help effectively remove algae, and eliminate virus, bacteria and other germs in water. It can be used in ultraviolet sterilizers for aquarium fish tank and pond. Bulb Type: UV-C Ultraviolet Base Type: 4-Pin Base Total Length: 6.22in. /15.8cm Power: 5 watts