FEATURE: 1.Patented Anti-reaction design, protect hose and changer of dental units from pollutant. 2. Powerful Torque; Quiet Operation 3. Single-port spray with improved water atomization, better spray coverage. 4.Patented Anti-retraction device, saves disinfection costs. DESCIPTION: 1.Back-flow Resistance Device, protects the hose and exchanger, of dental units, from back-flow pollutants caused by negative pressure. 2.By designing and installing our original one-way in-line main back-flow resistance device. It not only achieves the anti-suction , but also protects the rear hose and the gas circuit exchanger from contamination. Really achieves the goal of effectively preventing back suction, thereby preventing cross infection. ADVANTAGES: Convenient for doctors - Doctors no longer use regular handpiece, but use new handpiece every day. -No longer use high temperature vacuum sterilization equipment, reduce cleaning, packaging, maintenance handpiece costs and labor input costs. - Don't worry about sterilization and the infection caused by incomplete cleaning. - Protect the dental treatment machine from contamination, and completely solve the problem of dental handpiece cross infection. - Convenient for house visits and special use