Instantly converts one aquarium or terrarium into two. Provides a separate area for baby fish or aggressive fish. Each divider consists of two plastic tracks that mount on to the inside of the tank. The tracks are held in place by two clips that slip over the top frame of the tank. A clear divider then slides down the track to separate the tank into two parts. To ensure proper circulation and filtration, each divider has very fine perforations in it to allow water to flow from one side of the tank to the other. It is highly recommended that the tank have gravel or sand in it to keep the divider stationary. Easily trimmed to fit your tank. Available in four different sizes.