The Doc Well Fish cleaning pad is an indestructible and reusable pad made of a finer weave material specially suited to acrylic and plastic surfaces. The smaller size works well in areas that have surfaces that are difficult to reach such as found in mini-aquariums or equipment areas. Removes algae quickly and easily. The pad is recommended for use on acrylic aquariums and other plastic surfaces. Dimensions 3in x 3in.