The Smith & Wesson Sliding Door and Window Lock opens sliding glass doors and windows just enough for ventilation but keep them secure with the Smith and Wesson Sliding Door and Window Lock. This clever device can adjust to different sizes (from 28" up to 54") so you can open your door or window enough to allow air in while keeping children inside from getting out or burglars from getting in. Also includes a safety block which can help prevent removal of the door or window. Easy to install.