Three grades are used to identify the durability and quality of locks and deadbolts. The highest grade is Grade 1. This is the maximum security grade available and is ideal for commercial door locks. They can withstand much more abuse than the average lock and must be able to still function after 10 hammer strikes. Grade 2 locks are not appropriate for heavy-duty commercial security needs but they are still offer much more protection than anyone outside of the commercial industry would need. Grade 3 locks are for residential buildings and are not enough protection for a commercial building.