Electric garage doors are designed to prevent unauthorised entry protecting not only the contents of your garage but you and your family. Newer electric openers function as the lock where as an older opener would usually require a manual lock. We strongly discourage homeowners from attaching a lock once an opener has been installed. Accidentally locking the door can cause the opener to pull against the lock causing unrepairable damage to the garage door. If you know that your garage door is not going to be used for a while because of a family holiday, for example, the vast majority of openers feature a digital lock. The digital lock can only be lock/unlocked from with inside the garage meaning that a remote control for the door will still not be sufficient in opening the garage door until the digital lock has been unlocked/disarmed. Please Note: If no opener is installed on your garage door, a lock is highly recommended.