A residential locksmith Ballwin MO has the knowledge and experience for working with various types of locks and keys. This is a must for new construction areas with different locking systems to use that meets building codes. There are some companies that focus on just one type of lock or key, which may not be enough in the case of emergency. Residential locksmiths are considered to be experts in their field and they have advanced training while many other companies do not have proper licensing requirements