Creators of lab tests have their hands full when it comes to simulating a real live hurricane. All windows and doors have to pass a design pressure test, measuring of air infiltration, water resistance, and structural integrity at certain pressures, positive and negative (DP rating). For wind zones up to 120 mph a DP rating of 50 psf is usually required, 60 psf for wind zones up to 130 mph, 65 psf for wind zones up to 140 mph, 80 for wind zones up to 150 mph and 100 for larger than 150 mph. While in the beginning small missile impact tests were conducted with small steel balls to imitate flying gravel from flat roofs, most modern hurricane tests are either conducted with a 4.5 lbs (Missile C) or a 9 lbs (Missile D and E) piece of lumber. Depending on wind zone certification the missile is shot at a certain speed into three specimen either in one, two, or three impact points. The missile cannot penetrate. After the impact, the three specimen are cycled 9,000 times at varying positive and negative pressures (suction and pressure as exists in a hurricane) up to 1.5 times the Design Pressure rating. The glass cannot come out of the frames or show any openings larger than 2 inches. Henselstone's standard Design Pressure rating for all windows and doors is 65 psf positive and negative. All impact rated products pass the large missile impact test for wind zones up to 140 mph (missile D).