sera Glass Clear Small Magnetic Glass Cleaner

These magnets make cleaning the aquarium glass easy.The cleaning surface of the inner part removes the algae layers. The surface of the outer magnet is covered with a particularly fine synthetic mat that protects the glass. The magnets have an oar that allows attaching a piece of string for retrieving it.FOR USE WITH GLASS AQUARIUMS ONLY.SIZE: Small 33 x 70 mm (1.3 x 2.8 in.) for glass thickness up to 6 mm (0.2 in.)