The TQSF gravity-grading destoner is a product that was introduced from foreign technology in the 1980s and had been improved by NGM to target China market. It is mainly used for grading wheat after the initial cleaning and primary screening process, removing light impurities such as buckwheat, weed seeds, unhulled wheat, and insect-damaged grains, as well as eliminating sand, mud and stones. It can also be used for cleaning and seed selection of other grain crops such as barley, corn, soybeans, rice, brown rice, and rye.