Secondary protection for sliding patio doors and double hung (sash) windows. Hinge-type security lock constructed of clear plastic which bonds directly to the glass with 3M tape. No tools required for installation. Install at the junction of the active panel and inactive panel. 2 security flip locks on each card. Will secure 1 patio sliding glass door or 2 double hung (sash) windows. Security flip lock measures 2" x 3".