Security Grades for Locks
Locks are classified by a security grade. Grade 1 locks are mostly used commercially because they are generally more expensive than other types of locks. However, they offer the highest level of lock security. The most common residential locks are grade 2 because they still offer a high level of security but are more affordable. Anything rated a grade 3 is usually the least costly but is probably not secure enough to risk installing in any area that can be easily accessed, like an exterior door.