The so-called combination lock is a combination lock capable of preventing the universal key from being opened, characterized in that the key inlet and the outlet of the lock are at both ends of the lock, and one or more lock members are arranged between the key inlet and the outlet. The lock member is provided with a marble hole, a spring and a marble for opening and closing the lock, and a marble hole, a spring and a marble for the key to slide forward; and an angle between the lock groove on the side of the upper and lower lock and the key handle groove To close the keyhole. The utility model adopts a combination of a plurality of lock members, and an angle is set between the key handle grooves of each lock member.
During the unlocking process, when the lock cylinder is rotated, the angle between the key inlet and each lock body key groove is utilized. Poor, close the keyhole to prevent the opening of all kinds of master keys. At the same time, by using the anti-backup between the locks and the structure of the indoor anti-lock, the key can be left in the lock, so that the lost or prepared key can be retrieved, which is more safe.