Heavy Duty 4 Swinging Bar Slide Bolt Entry Security Door Guard,brass Plated by Ultra Heavy Duty, Cannot be unlocked from the outside, Unlocks easily from the inside, Allows doors to be opened slightly for viewing or ventilation while resisting forced entry, Ideal for limiting door openings in residences, Guard is easy to install and operate, Increased security for wood or metal doors, Furnished Screws Included, Allows for 4" maximum opening, Brass Plated Finish