[A Snake]

Stainless will work fine, like Jeff said. If you're worried about it coming loose, use metallic self locking nuts. You can even make them yourself using a small sharp chisel. Just make a triangular pattern of three marks at the thread edge. Done right, the chisel marks will slightly collapse the first thread, making it hard to turn. They are also easy to get at a good hardware store. The poly lock inserted plastic locking type will melt.

Al