The best window guards, according to the CPSC, do not allow windows to have an opening of more than 4 inches. They should screw into the side of a window frame, but also allow for escape during an emergency. Website MedicineNet states that you can place permanent window guards on windows if you live on the seventh floor of a building or higher. The bars on the best window guards are spaced no more than 4 inches apart.
Window guards are not necessarily the same as window bars, as they are not resistant to break-ins from thieves. The quick-release hardware that some feature may be simple enough for children to operate, so it is best to choose one that has an emergency release mechanism that is more difficult for young children to use. Many window guards support up to 60 pounds of downward force, so it is not safe for children who are heavier to hang from the bars. If you purchase a window guard, you should not install it on the part of the window that is outdoors because exposure to inclement weather can weaken the safety device.
You can purchase window guards at home improvement and hardware stores, or from a company that specializes in the installation of windows. There are several colors and styles from which to choose, so it is important that you know the exact measurements of your window before you go shopping.
In addition to using window guards to prevent accidental falls out of windows, the CPSC states that you can also use window stops. Window stops, popularly used at hotels, do not allow windows to open more than 4 inches. Some companies state that the window screens, or mesh window safety guards, sold are also effective for preventing accidental falls. However, the CPSC states that you should never depend on window screens for preventing such incidents.