It looks like a computer mouse, but is a very loud personal alarm that may be carried by a jogger, night-shift worker or just someone that might be threatened getting across the parking lot. If the loud sound does not frighten off an assailant, it will at least attract plenty of attention. A bonus feature is a "penlight" flashlight that may be used to locate a lock, foot path etc.Operates on two AAA batteries, which are included. MG222