Guardian Angel is well known in the realm of safety products for preventing falls from windows. This product offers high quality construction with 4-inch spacing between bars to keep children in your home safer. This product may be used with single or double-hung windows as well as sliding and casement windows. Easy installation with included hardware. Parents will appreciate the convenience of quick release buttons for potential emergency situations. Three sizes to choose from. Lifetime Manufacturer Warranty.Works for windows 35 to 58.