This is a 250-watt REPLACEMENT light assembly used for the Natural Green Extra Bright Systems. This is simply a replacement bulb and wire for the entire Underwater Fish Light system. This part WILL NOT work on its own. An Underwater Fish Light control box, photocell, and GFCI Plug is needed for a complete functioning unit. This Replacement Light Assembly is not compatible with the Classic Natural Green 175-watt systems. If you are unsure of what type of light assembly you would need, please call us at 941-391-5846. This is a part, NOT a complete system.