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One regulator to avoid might be
It is a 2 stage regulator I bought off Ebay a number of years ago probably 2013-2014. I think i paid $45 + shipping for this regulator brand New in packaging.
It has less than a dozen flights but gives frustration adjusting.
I still consider it usable but with cation. The first year (maybe 2 or 3 flights) no issues. After warranty ended started having issues.