The body of the drain backflow preventer is designed in v-cup shape, ensuring the smooth draining and water flowrate; folding winkles between the binding, increase the tightness and compactness. Drain Backflow Preventer is made of good quality silicone, totally environmental-friendly material; No smell. No worry about deformation after stretching, super flexible; Ever-lasting and durable，Protecting your family health. As sewer is connected with the underground septic tank, unhealthy things may enter room from smelly drain. So it is necessary to install drain seals in bathroom, basement, garage, laundry room. The floor drain filter with the automatic closing design, seal stinky smell and odor from sewage gas; Prevent the drain water from backing up to the room; Anti- water leakage and overflow.