I do believe Zinger is out of business, isn't it? I remember the owner just shutting things down to retire, and then a few months later was tragically killed in a plane crash. I , myself, have had very little success with Zinger props except for use on my SIG Primary Force ARF with a OS .32F on it. The Zinger Pro 11-4 so far has been the best prop for that combination.
HAPPY NEW YEAR!,
Dan McEntee