TubeNet

short answer.....they are different kinds of rigid plastic.

For more details:

http://en.wikipedia.org/wiki/Lexan

http://en.wikipedia.org/wiki/Lucite

bloke wrote:Is anyone currently offering Lucite tuba mouthpieces?

Looks like the Josef Klier line is available in "Plexiglas/perspex" (for 114 euros vs. 83 for silver-plated):

http://www.jk-klier.de/

I use a lexam rim on my DE set up, very comfortable, can't say there's much of a sound difference for me but as Doug says, it feels smaller than the same rim in metal.

CB