Excellence best describes the ingenious design of this high efficiency window. Our casement window permits 100% ventilation which is twice as much as our double-hungs. Dual arm operator hardware gives the casement a clean look and allows a full 90 degree opening for more ventilation and easy cleaning from inside the home. The screen is mounted from the inside, staying clean longer and is easily removed when desired. All hardware is made from hardened steel and finished with patented Corrosion Guard.