This is a fun little toy, although it's not clear exactly what's "self-contained" about it. It's loaded with features, from the one-touch glow in the dark button to the five-speed pulse function. (OK, it can be a pain if your favorite speeds are #1 and #5, since you have to pass through the other functions first each time you want to switch.) Two sizes are available, the medium (six inches) in sky blue and the large (six-and-a-half inches) in deep purple. The six-incher takes two AA batteries; the large requires two C cells.