This is a 20" Coralife Aqualight 28 watt fixture with a 50/50 bulb in it. It has only been used for 1 month. MAKE ME A OFFER!! Staten Island pick up only.
A 20 gallon high is 24" wide and this light is 20" wide. It will fit on top of a 20 high if you have a glass cover on the tank. All you have to do is take the legs off the light.