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.