Isn’t that cool when you got a glowing charm on your phone when someone calls? yeah, having that is a long time ago story, but this one is a little special cuzz it comes in a bulb shaped. It is useful some how when you are having your class or meeting, it will lets you know when there is an incoming call. It is powered by 3 x SR60 Batteries & will be suitable for 1800/1900 MHZ mobile phone. It measures 3 x 1.6 x 1.6cm. & I am not sure if it is made of glass or not. Get one of these bulbs for $10.75 usd.