This swing bar door guard will increase peace of mind when answering the door by allowing the door to be cracked open slightly for viewing. When engaged, a ball on the keeper interlocks with the bar lock and prevents an intruder from pushing their way through. Although a standard swing bar door guard can add great security to your home, condo, apartment/flat, or hotel room, there has been some concern over the wide availability of emergency release tools, which are meant to release swing bar door guards in cases of emergency. We have improved upon the standard door guard design and added an innovative backup thumb turn security lock that blocks the release tool from disengaging the door guard latch. In cases of emergency, hotel security or emergency crews can pop the thumb turn off of the unit by applying approximately 100 lb. of force to the door. (Note that 100 lbs. of force is much greater than a simple kick in, so the emergency release feature does not compromise your security). Additionally, after the thumb turn lock breaks away, the unit still operates as a traditional swing bar door lock and a specially designed anti-Lockout emergency access tool is required to swing the door guard out of place. To help prevent forced entry into your home, it is always a good idea to engage the backup thumb turn lock whenever you are not actively using your door. Defender Security by Prime-Line offers a full line of security hardware designed to protect your home and loved ones."