Thread doesn't really work, especially in a taller tank like a 29 gallonOtherwise very good producy

3gal cubeUpdate after use - I still think this is a good magnetic cleaner, but I really wish it floated. Floating makes cleaning so much easier to move between the sides. It does include a string to connect the magnets, but making to string long enough to get to the gravel edges still allows the magnet to fall to the bottom. Switching sides can be accomplished without it falling to the bottom, but that can be a little tricky. If Marina would make a floating version, I would certainly buy one. Until then though, I need to knock off a star (for ease of use only).Inside the aquarium, the cleaner has a profile of only 2.5cm, taking up very little space. This is a good size for my 3gal cube. It moves smoothly and makes quick work of glass algae. Magnets are plenty strong for the 4mm thickness of glass.

it works very well on my glass aquarium