The sole purpose of auxiliary locks is added security, and they are most often installed in combination with one of the aforementioned lock types. Auxiliary locks are placed on the interior-face of the door/door frame, and most frequently entail sliding locks and chain locks. In this case, a chain attached to the interior-face of the door can be secured by inserting the end into a metal bracket on the adjacent door frame or wall. Auxiliary locks are generally inexpensive and therefore easy on your wallet, extremely simple to install, and can be used in conjunction with most primary locks for additional security. Despite their versatility, auxiliary locks can be easily undermined and therefore are best used in addition to a more stable locking mechanism.