I have a new set with c370 as primary and octo so was just curious.I don't know, and don't really care. It's a perfectly good regulator and removing the decorative steel piece has taken care of the snagging problem. Scubapro just fell a notch in my book for customer service. I've been a customer since my MK5/109 in 1972. My family of 4 has 8 Scubapro reg sets.