The ERA 826 Window Bolt Dual Screw Polished Brass fits most sash windows and is concealed from the outside when fitted. It offers added security as the screw can only be removed by the use of a key. Barrel Fitting Frames  The brass barrels are driven into both the inner and outer sash frames and the key operated bolt screws through both sashes to lock the window. Each pair of dual screws comes complete with one key and full fitting instructions. Window Security Tip Remember to remove all keys from locked windows, when not in use, and keep them out of sight in a safe pla...