This product is suitable for replenishing water in fish tanks with cylinder- wall thickness of 5/6mm and -8mm. with international standard coke-bottle. Usage: It can be used for the fish tanks wall with -8mm thickness, and it has two states- corresponding to the fish tanks wall with 5mm and 6mm thickness respectively. Cut_off the differential pressure pipe (the water end is an oblique-mouth), a long and a short , and the short is the highest water line-. When the short pipe is completely - to the liquid surface~, it will start to - water, and the short pipe will stop to replenishing water. This product needs to bring its own water replenishing bottle, and the thread of the product is suitable for domestic standard coke-bottles. Built-in reduction device can effectively reduce . (Note: not completely ). The length of the (manually cut) allows you to adjust the water .