Back to Nature Aquarium Backgrounds are an amazing addition to your aquarium and really make you feel you have a real piece of nature in your home!! Back to Nature Slimline backgrounds are approx. 10 mm thick and come in two colours White Limestone and Red Rock. Slimline backgrounds are available in several sizes that interlock this means they can be installed easily and quickly in nearly any tank. Slimline backgrounds are produced to the same superior quality as all other Back to Nature backgrounds. This means the colour will be preserved and the background will keep it\'s lustre even after years of use. The Slimline assortment consists of two heights 45 cm (for 50 cm aquariums) and 55 cm (for 60 cm aquariums). Each height consists of four sections A and B that are 50 cm (with a different layout) C that is 20 cm and D that is 10 cm. Using these four sections is it possible to combine a background that completely covers the back of any size of aquarium. 50cm x 55cm