Night latch
Type of keyed door lock
From Wikipedia, the free encyclopedia
Overview
Night latches are usually rim locks[4] and are available as deadlocking (automatically locks once shut) and non-deadlocking versions.
Historically, such locks were intended for use at night-time, hence the name.[5] The keyless egress that they offer is a valuable fire safety measure, but may be a security risk if breaking a glass panel (usually in the door) or a nearby small window allows an intruder to reach the knob inside and open the door from the outside.