The product to be sieved is sent to the sieving area from one or more inlet pipes. The product, reaching each passage in the Square Sieve, moves through the pressure pipe and moves in a way that the pre-set flow paths are vertical and horizontal during the time it is in the passage. It is classified according to the diagram and it is discharged out of the pipe from the pipes at the bottom of the passage. There are formica coated sieve boxes and teloras inside the sieve cabinets. The product entering the sieve can be separated into 7 different classes. Up to 22% increase in sieving area is achieved with the use of wide crates. Up to 32 crates can be placed in each passage of the sieve. At the same time, there are observation pipes for the control and monitoring of the product.