1. It removes stone, clod by adjusting wind pressure and amplitude higher specific gravity materials (stone) will sink to the bottom and move up towards higher edge under stress of vibration friction; lighter specific gravity materials (seeds / grain) moves down towards lower edge. 2. Equiped with internal fans, no need to install wind net system. The Fans and vibration system are equipped different motors, non interference . 3. A transducer speed regulator help adjust vibrating frequency for different materials to achieve best effect. Small material (millet), medium materials (mung bean, soybean), large materials (kidney beans, broad beans )