This is a set of two anti-theft door alarms. *Individual sales are also possible, so please inquire. However, they will be more expensive than the set. These anti-theft alarms can be easily attached to doors and windows. They alert you with a loud alarm when a door or window is opened. Installation is easy, just stick them on with double-sided tape. They have four modes. This is an unopened item. If there are any initial defects, please contact the manufacturer.