The strength of a lock is graded from strongest to weakest on a scale of 1-3. Grade 1 locks are typically used on commercial properties as they are the most secure and durable locks available. A lock graded as 2 or 3 on the other hand is suitable residential use. It is, however, generally advised that busy homes use a more robust grade 2 lock which is also suitable for light commercial use. In addition to supplying locks, a commercial locksmith will also offer an installation and repair service for commercial security systems. This can involve the supply and maintenance of safes and cabinet locks, as well as more elaborate master key systems and panic bars.