As already said, I think it's for carrying copper pipes, etc.
The main advantage to carrying them this way, is that they can be locked up, away from thieving scumbags :)
oh prof, that brought back memories.....at school we were taught to blow bubbles from glass tubing and put bends in the glass to trap stuff in experiments. We made out own thermometers by blowing a glass bubble at the end of hair tubing then warming and cooling the air to suck dyed alcohol into it. I bet kids aren't allowed to do that now!