"Fan's Automatic and Synchronic Open and Close Screw-Nut Mechanism" is a great invention in mechanical screw-and-nut history. It is granted patent rights in more than 20 countries, such as China, United States, Germany, Australia, Canada, France, Italy, England, Switzerland, Sweden, Austria, Netherlands, Spain, Belgium, Brazil, Japan, Russian, Mexico, India, Singapore, South Korea, Taiwan, etc.