I don't have a picture of mine, and none of these are the one I have, but this is how they're shaped:
http://images.google.com/images?hl=e...&aq=f&oq=&aqi=
They're the type you usually see on skateboarders and BMX bikers and such. I also plan on wearing mine when I start learning jumps and such in skating, because I hear it's advisable to do when learning more dangerous stuff (I've already been saved once by having my hair in a bun, but I won't always fall on the back of my head).