- Hose length is manually cut to adjust water flow for your tank. - Usage and compatibility: suitable for aquarium walls with thickness 8 mm, with two states for walls 5 mm or 6 mm thick. - How it works: cut the differential pressure pipe (the water end has an oblique mouth). Use both a long and a short tube; the short tube marks the highest water line. When the short tube is fully submerged, it fills with water and the short tube stops replenishing water. - Noise reduction: built-in noise reduction device helps reduce running noise, though it may not be completely silent. - Application and contents: this product is suitable for refilling water in aquariums with cylinder wall thickness of 5/6 mm and 8 mm. Comes with an International Standard Cola Bottle. - Practical scenarios: - Daily top-off in a nano or small tank to compensate evaporation, maintaining stable water level. - Refilling after a partial water change without overfilling, using the short tube as a water level guide. - Use in tanks with 5/6/8 mm wall thickness to ensure appropriate refill behavior during routine maintenance.