Sunwayman V10R xml.
Very nice light that I've been EDCing that last couple months. Unfortunately, I just broke it today

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Before it broke the brightness control ring was excellent. At its lowest it was a very low low (dimmer than the lowest low on my Zebralights), and then would smoothly ramp to full brightness.
Unfortunately, today I accidentally put the the battery (IMR 16340) in backwards and then hit the power switch. The light didn't turn on, and I clicked the power off when I realized what had happened. The light couldn't have been in the on position for more than 2 seconds.
Sadly, 2 seconds of the battery in the wrong orientation was enough to break the light. It still works... but the tuning on the control ring is now all messed up. The lowest setting is now much dimmer than even the default lowest setting. I can't even tell its on unless I look directly into the led from short range in a completely dark room. As I turn the control ring towards high, the light continues to stay quite low. The first 2/3 of the ring now gradually bring it from barely visible at close range in a dark room to perhaps 10 lumens. Then about 2/3 of the way through the turn it turns almost instantly to max. Now it ramps from maybe 5% brightness to 100% over a just a couple millimeters of turn.
Technically, the light still works. It still runs at max brightness, and its lowest low is actually even dimmer than when it wasn't broken. But because the light no longer evenly ramps up it's extremely difficult to get just the right brightness setting. Never NEVER put in the battery the wrong way in this light. It might even be a good idea to install a plastic or foam washer to protect against incorrect battery installation.