The Superfish high quality floating magnetic cleaner helps you clean your glass without getting your hands wet. In a variety of sizes to suit every tank size and thickness. The pad on the inside gets rid of tough algae spots without scratching. Not suitable for acrylic tanks. Mini 9.3cm x 4.5cm x 12.4cm Small 12.2cm x 5.5cm x 16.9cm Medium 12.4cm x 6 x 16.9cm Large 12.6cm x 5.5cm x 16.9cm