The Mirrycle Jellibell is a fun way to let pedestrians and other riders know you're coming! The Jellibell has a see-through top so you can see the gears spin as it rings. It's weatherproof, too!
I installed this in my daughters first bike, and she loves it. We ride daily at a local park that is very crowded, and she is able to let people know she is there with out yelling "Excuse Me!". She can work it with one hand, and keep the other on the handle bar, and that's important while she is learning to ride a bike.