Suitable for refilling water in aquariums with cylinder wall thickness of 5/6 mm and -8 mm. Fits international standard cola bottle threads. Key benefits - Automatic water refilling to help maintain stable tank levels - Built-in noise reduction device lowers operating noise (not completely silent) - Uses its own refill bottle; thread compatible with domestic Coke bottles for convenient sourcing - Flexible compatibility: two operation modes for wall thickness 5 mm or 6 mm, and suitability for -8 mm applications Product features - Compatibility: aquarium walls with thickness -8 mm, with two modes for 5 mm or 6 mm walls - Connection: fits standard cola bottle threads for easy refill bottle attachment - Noise reduction: integrated device reduces noise during operation - Refill method: requires its own refill bottle; threaded to suit domestic Coke bottles - Orientation and flow control: the unit provides a long and a short intake; the short intake defines the highest water level line - Operation trigger: use the differential pressure adjustment; the intake end is an oblique mouth Usage scenarios - Automatic top-off for freshwater or planted aquariums with 5 mm or 6 mm wall thickness - Refill setup in an aquarium where a standard cola bottle refill source is preferred - Quiet operation in a home or office tank, with adjustable intake for different water levels Please ensure proper selection of the long or short intake according to wall thickness and desired water level. When the short intake is positioned at or near the water surface, the device will begin refilling and stop once the water reaches the defined short level.