QBS-0049 is a Klaxon Signalling System, a device used to issue a loud, warning alarm in order to alert occupants in a building in the event of an emergency, such as a fire. This particular system can be installed internally or externally, and it is powered by a wall mounted transformer, from either a 230VAC or 24VAC supply. The unit can also be integrated with other Klaxon devices, each using either a relay or open-collector output for connection. The sound output is a loud, continuous tone of 86db at 1 metre, which can be easily heard throughout a building and is capable of being heard by occupants over other noise.