All my lights are for use but admittedly I have so many that many will sit unused. My Oveready zero res being one of them.
It's all Oveready stuff, being a direct drive turbo head with an XPL, 18500 skinny tube with a P60 adapter(18650 protected inside), re-anno'd Surefire tail cap and a zero res shorty.
I can also get mine to momentary when I unscrew it just enough. The light also works great in either hand position with a one handed twisty operation.
The head works just fine on a McClicky and doesn't require a zero res apart from form factor and twist operation.
Good luck with finding a zero res, don't see many these days. I'd be talking to Kitrobaskin if he's will to let one go.