Abstract: An easily adjustable grader for sizing and sorting food products, especially shellfish such as shrimp. The grader includes a series of parallel rotating rollers attached at either end to drive chains. The drive chains include adjustment levers attached rotatably at each roller position. The levers have a first arm terminating in a rolling wheel and a second arm whose end conforms to the chain. An adjustment rail is positioned above each chain along the length of the grader. The wheels of the levers ride along cam surface on the underside of the rail. Rail adjusters at each end of the rail raise and lower each end of the rail to change the spacing between the cam surface and the chain along the length of the grader. The pressure exerted by the cam surface on the lever causes the chain to kink in proportion to the distance between the cam surface and the chain, which adjusts the gap between consecutive rollers. The widths of the gaps determine the size gradations of the grader.