Italian Pipes

Why do glass pipes have a carb on them and metal ones don't?

I'm talking about pipes to smoke, uh, you know... So most glass pipes I see have a carb and metal ones don't. Is there any reason for this?

Public Comments

1. most glass are double ply, meaning the bowl is inpressed into pipe, needing air. metal pipes have stems
2. I noticed that too. I don't know why. When you find out let me know.