JBL Floaty II L is a algae magnet aquarium glass cleaner which is swimming, not sinking for aquarium glasses up to 15 mm thickness. No need to fish around in the aquarium if the inner part of the magnet accidentally comes apart from the outer part. The inner section of the JBL Floaty II magnet cleaner is with angled projections on two edges to protect the silicon adhesive seams. One end of the inner section with flat extension for easier cleaning behind pipes, heaters etc. Extremely light-weight material with strong magnetic field. Do not use with plastic tanks, on acrylic aqaurium glasses.