This 4 digit combination locker lock is suitable to install on metal, wooden and plastic doors. In case of lost the password, people can use master key to open the lock and find the correct password with search tool. Equipped with 10000 key combination, people could enter the personal password according to their need. What's more, this 4 digit combination locker lock has master key for emergency opening. If you always forget the password, this lock will be the best choice. What's more, it is an ideal application for school, airport, railway station, spa, sauna, gym, workplace, office, supermarket. http://www.emakelocks.com