This chain door guard is constructed of extruded brass and comes in a satin nickel plated finish. It features a 6 in. long, 8-link welded steel chain and all installation fasteners necessary for complete install. When this chain door guard is fully assembled and engaged from base to keeper, the chain will extend to 4-5/8 in. To determine the maximum distance it secures a door for safe viewing or ventilation, subtract the thickness of the door from 4-5/8 in. (approx. 3 in.). This chain door lock can be used on a variety of door types. The keeper's mounting plate can be mounted on, or beside the door's casing. The smaller chain-holder base measures 3/4 in. wide and the wider chain lock keeper measures 3-5/16 long; both with a height of 2 in. This chain door guard also works great as a child-safe security device which can help prevent little ones from fully opening doors and entering or exiting into dangerous areas.