At your preset time the propeller launches into the air with all the manic energy of a Tazmanian devil. The siren is inescapable, the landing could be anywhere in your room, and it won't shut the heck up until you get up, find, and then replace the propeller on the base of the alarm clock.
All the usual functions of a modern digital alarm clock are included, such as a snooze function, and the digital display has a soft blue back light.