I purchased mine in March of this year , and it has 02 2017 I am guessing that is the manufacturing date.
15 yrs from manufacture date is the rule. If your dive shop is going off the last hydro date, they're doing it wrong & could be getting themselves in a jackpot.This is from the Air Venturi owners manual, page 2:https://www.pyramydair.com/air-gunsresources/manuals/AV-carbon-fiber-tank04500-psi-90cu-in.pdf"Composite cylinders must behydrostatically tested every 5 years.Plus, composite cylinders have amaximum life of 15 yearsfrom their originalhydrostatic test date.ALWAYS make sure your cylinder iswithin its retest period."