This patio door security bar is constructed from aluminum and features a telescopic design that allows it to adjust to fit nearly all standard patio door openings. Unlike typical patio door security bars, this adjustable product does not require you to cut the unit down to size with a saw. You simply press in the tension release clip to extend the length or reduce the length. The adjustable design also allows you to secure your patio door in an open position, so you can safely allow fresh air into your home. When not in use, simply swing the patio door security bar up and out of the way. When the unit is in use, it must be properly secured into the saddle. The saddle consists of a metal component along with a plastic component and both must be used together. The metal saddle provides primary support and prevents the door from being forced open. The plastic saddle, which sits in the metal saddle, provides secondary support and features a "one-way" operation mechanism that allows the bar to swing into place easily, but prevents the bar from swinging out of place without user intervention. Potential intruders may try to insert a wire between the stationary panel and the sliding panel to swing the door bar out of place, but the dual saddle system can prevent that from happening. This item can be used on metal, vinyl or wood sliding doors & windows. Note that a properly functioning sliding door handle with a reliable latching/locking mechanism is the primary and most important way to secure your sliding patio door. Patio door security bars are designed to be used as a secondary security solution. Prime-Line offers a full line of patio door handles, latches & rollers designed to keep your sliding door functioning like new, and our Defender Security line features multiple security solutions that will work for nearly any sliding patio door. Browse our full selection on Amazon.