The KEY size grader classifies the products by the difference diameter of the product or removes dust, stones and other foreign matters.

The machine tool of the size grader is composed of a series of rollers of different sizes. Each roller contains a stainless steel roller and a "finger" rubber rolling drum arranged on the roller shaft according to a certain distance after calculation. A hole is formed between the "fingers" on each size of roller and those adjustable roller drum for foreign matters to be removed from the grader. The remaining good products are transported forward to the end of the grader with the linear direction of roller rotation.

Product application: beet, root products, carrots, onions, potatoes, processed apples.