Delta Airzound Bike Horn
This bike horn emits a very loud sound (similar to those pesky airhorns you hear at graduation) so that you can warn cars when you need to! It also features volume control, as well, so it's not always ear piercing. Plus, you just refill it by pumping it up with air via your bike pump. I can't tell you how many times I've wished I had a loud horn on my bike. It's so scary to want to honk something, but have nothing!