This is an item commonly used by businesses such as retail stores and restaurants. It allows emergency exit in case of fire, but prevents customers (and employees) from exiting the building except through designated doors during other times. Look around. Wherever you see “Emergency exit only. Alarm will sound” you have encountered an exit alarm. This is used in situations where locking a door would violate fire code, but leaving it unsecured would breach security. Exit alarm products are available either with or without locking devices included. See also panic device.