Lok N Blok Max requires no tool, no screws, and no chains. Simply lock the deadbolt and slide Lok N Blok Max on.,Lok N Blok Max is made of ULTRA strong, durable, and lightweight ABS plastic. No need for heavy and bulky metal devices that scratch your door.,Lok N Blok Max Helps to Prevent Key-Bumping and even prevents the lock from being turned with the correct key, which can be useful for keeping people who once had a key from re-entering, like an ex room mate or renter etc.,Lok N Blok Max provides more piece of mind and helps to keep your family safer.