Jeld-Wen Premium Atlantic Jeld-Wen Aluminum windows provide the reliability you are looking. Our aluminum windows include a unique performance feature - it's our patented silicone-injected corner key, which is created by injecting silicone into the corners for added strength. This feature also ensures the window is reliably weathertight. Double Hung windows feature an upper and lower sash that slide vertically past each other in a single frame. Tilt-in feature makes cleaning a snap even on the exterior of your windows. ImpactGard protection is engineered and tested to stand up to the strong impacts of windborne debris, as well as the harsh conditions inherent to coastal areas. With the industry's leading laminate glass technology, windows and patio doors with ImpactGard protection can withstand a nine-pound piece of lumber striking the glass head-on at approximately 34 miles per hour. In addition, it significantly reduces sound transmission, blocks up to 95 percent of harmful UV rays and offers superior forced-entry resistance.