The picture you get off the roll at the store. It has a nice backdrop that is not distracting but rather enhances my rockscape/sand and makes the tank look deeper from front to back than it already is. When water is in the tank it just gets dark unless water drips between the backround and the back of the tank. of course the backround goes on the outside. Is vasalene safe for acryllic or will it attack the plastic like ammonia windex will ?