auto top off aquarium fish tank water refill system Great for nano tanks, use with the principle of differential pressure to automatically refill water, simple and practical. You need to prepare 0.5-1.5L (16.9-50.7 FL Oz) plastic water bottles such as EVAIN / Coca Cola / Fiji yourself. Built-in noise reduction device can effectively reduce noise. (Note: not completely silent). Screw-free, no damage to the tanks. Made of corrosion-resistant ABS material, which is also usable in saltwater. The length of the tubing (manually cut) allows you to adjust the water level. Suitable for tanks with 3-10mm/0.12-0.39in wall thickness. Note: Incompatible with rimmed tanks and curved fish tanks; and tanks with 3mm/0.12in or 5mm/0.2in thickness wall need to use the self-adhesive gasket (included). A reliable gadget during business trips or travel. Compatible with fish tank, tortoise tank, planted aquarium, saltwater aquarium, etc. For tanks longer than 40cm/16inch, it is recommended to use 2 refillers together.