Introducing the "Cerium Sponge" with a pattern that can remove stubborn calcium stains. Uses a special micro-abrasive particle "cerium oxide" that is much finer than normal abrasive material, so it can be cleaned while touching the glass surface. In addition, when polished thoroughly, cerium oxide reacts with the glass and can remove tough white stains such as calcium. (Note: When cleaning calcium, please remove water from the aquarium before cleaning the water) Sponge part: Width 2.0 x Length 3.5 x Thickness 1.6 inches (5 x 9 x 4 cm); Scraper part: Length 13.8 inches (35 cm).