Made of plastic and super strong magnet, good absorb ability and powerful magnetic attraction. Perfect for cleaning algae and scum off of the inside of your aquarium the easy. Size: 3.7in * 1.7in * 2.8in Easy to clean. When you move the outer magnet, the inside magnet follows, hence clean the glass. Just enjoying the happy time when cleaning. Floating design. The brush will not sink into the farthest depths of your fish tank as it is floating, very convenient to use never mind weting your hands. Strong magnet for using in tank with different thickness(less than 8mm/0.03inch); suitable for 50-80cm / 19.6-31.4 inch (under 50 gallon) fish tanks. Soft anti-slippery handle can make your hand comfortable and improve your cleaning action. Labor saving and time saving.