ONLY FOR INSWINGING DOORS WITH 3MM CLEARANCE - This portable, industrial strength door security device prevents unwanted entry. It takes just moments to fit in the gap under an inswinging door without needing tools and uses displacement of force to barricade the door against an attempt at forced entry. TRIED & TESTED - At twice the size (a height of 192mm), Lockdown is the heavy-duty big brother of award-winning original travel safety device DoorJammer. DESIGNED FOR COMMERCIAL USE - Created for emergency deployment in public buildings, schools, offices or hotels, this is the last word in portable stopping power. QUICK SETUP & RELEASE - Takes only seconds to install and remove. No tools are required to implement this revolutionary home security device. In case of emergency, the quick-release easily removes the Lockdown with an upward motion. HIGHLY VERSATILE - Compatible with all types of flooring, the innovative system of hinges and angles anchor the Lockdown firmly to carpeted, tiled and laminate floors when outside pressure is exerted on the door.