1. This top-down series seat is not included in the products and can be directly used in copper-free environments;2. It has multiple specifications and can be used in various frequency oxygen systems;3. The flow performance is improved, and the flow rate of the same capacity as the inner diameter of the radon pipe can be achieved;4. It is convenient and quick to unplug and plug in the pipe connection, and the quick connection part of the pipe is safe, reliable and durable.