Generally, the common hidden locks are divided into three, four, and five sections. They are often used for the second entrance door or the first-floor door of an old apartment. In many cases, these door locks are easy to be damaged. Thus, it is better to choose a concealed multi-section lock, which the lock head and the lock box are integrally formed. Usually, the locks with more than five sections are integrally formed. The material selected is heat-treated steel with a hardness that is not easy to be broken and pried. To improve the safety, you can choose the anti-vandal door lock, some are using steel nails in the lock to prevent the electric drill from damaging the structure, or use higher grade steel.