A screen formed by piano wires stretched tightly, lengthwise, on a frame 2 to 3 ft (0.61 to 0.91 m) wide and 4 to 8 ft (1.2 to 2.4 m) high. The screen is set up at an angle of about 45 degrees and crushed material is fed to it from above. The mesh size varies from about 4 to 16. Because there are no cross wires, and because the taut wires can vibrate, there is less tendency for blinding, but some elongated particles inevitably pass the screen.