ScubaPro R109/R156? Correct me if I'm wrong, but the "R" series are plastic. I think the root of the confusion is due to the existence of the R190; a very good regulator, but still not in the class of the Adjustable 109 or the Balanced Adjustable (156.) I don't know why it bugs me to see eBay adds and even some of my mates here refer to their beautiful chrome regulators as R109 or R156. "R" means cheap ugly plastic....please stop.