The Clear-Seal basemat is an alternative to the white polystrene tile normally used between an aquarium and the surface that it is sited on. Manufactured in a dense black foam, it will even out slight imperfections under the aquarium However, this is not a substitute for a flat and even surface. If the original surface is not flat, damage may occur to the aquarium. The basemat can be easily cut to size for non standard aquariums.