A mechanically operated warning device (read: doesn't require any electricity (a firm tug will do it). This Trip Gong is vital safety equipment in apartment houses and commercial buildings in the event of power failures you can still alert residents. Construction jobs, factories, mines, schools and engine rooms all benefit because you can hear it above the noise what's that you said? The gong itself and the mechanical lever action are made of brass. The base is steel with black powder coating. This one rings loud and true. Please note, a small number is kept in stock, but orders for multiple bells can take a few weeks to a few months to fulfill. Made in USA.