Just insert it on the door frame baffle and close the door. It is adjustable. You can tighten the screws by yourself until you know it is firm Make of zincs Alloy, which is strong and for a long terms. It has strong firmness Small and light weight. It is easy to carry, and you can put it in your pocket, bag, or suitcase, taking up little space It can protect security and privacy when going out, business trip, vacation or living alone, unauthorized entry into room Suitable for travelers, college students, singles and more. You can use it at home, hotel, school and more, Manufacturer: AMISENK