The control sieve is used for the final control before packaging in the packaging unit of the flour factories. The product arriving at each passage of the square screen enters through the pressure pipe and moves vertically and horizontally through the pre-set flow paths along the passage. The final checks are made after the flour sifting process. The flour, whose last checks are made, is directed to the bagging process. Apart from flour and semolina factories, it is used in processing plants of wheat, corn and similar grains, in feed mills, in various food products processing plants for the final screening of mixed feeds and for the sifting of large-grain corn, crushed pellet feed, barley, oats and similar processes.