High-Security Sliding Window Lock - 3-Second Installation Instantly lock sliding windows and doors - no drilling or tools needed Place on window or door track to lock shut or allow partial-opening then just tighten thumb screw Prevents window from being forced or pried open from outside; easy removal and reusable Fits most vertical or horizontal sliding windows & many sliding doors to 1/4" maximum track-width Heavy-duty extruded aluminum won't rust or corrode; sold individually, order in any quantity