1. This series of frequency source products are not included and can be directly used in prohibited environments;2. With multiple specifications, Huangfan is willing to be used in various frequency radon systems;3. The circulation performance is improved, and the flow rate with the same capacity in the remaining pipe can be passed;4. Plugging and unplugging the pipe is simple and convenient, and the quick-connect part of the pipe is safe, reliable and durable.