They are the underappreciated red boxes sitting on the walls of major building. Keeping you safe from being burned up in the ravenous flames of an inferno, they are FIRE ALARMS.
How Fire Alarms Work
Light - generally a flashing srobe light that blinks on and off to tell you that flames are near. Exit the vicinity. Note: staring at flashing strobe lights is probably a bad idea. duh.
Speaker - usually emitts an unpleasant ear-splitting noise meant to warn you there is a fire. It would be wise to exit the building. Use exit signs to help you.
Handle - pulling this will trigger the building's fire alarms. Do this ONLY if a fire exists OR if you wish people to get very pissed off at you for a false alarm. Either reason is acceptable.
Want a Fire Alarm? Check these sites out.
Everlert, Inc - makers of consumer safety products
Allied Fire Alarms & Escapes Co. Ltd. - another builder of fire alarms
Fire-Lite Alarms. - If you haven't found a decent alarm yet, try this site