With the help of a key, detachable padlocks and padlock keys can be opened. The devices are used in a wide range of applications to prevent unauthorized access, theft, or vandalism. Padlocks with combination numbers can be cracked by trial and error, while keyed padlocks cannot be shimmed because they do not have a dial. Each padlock in the master system has its own key, which can be used to open all the padlocks in the system. However, the master key can open all padlocks in the master system. As opposed to cylinder padlocks, coreless locks can be re-keyed or re-programmed by replacing the cylinder core.