Classifies ground product using an oscillating body and screen boxes of different sizes in each passage. After sifting, product travels through channels in and between the frames and main chassis to the outlet and inspection pipes. Frame surfaces are Formica-coated; insulated outer passage covers prevent flour leakage. Product enters the top passage in one or two streams and flows down through the boxes. Spacers between main frames increase discharge volume and prevent accumulation. Screen frames are clamped by jacks on the outside. Flexible suspension rods attach the body to the factory structure. Feed enters at the top and discharge is at the bottom.