My wife had been carrying a Fenix single CR123A flashlight on her barn keychain for years. It was a great light and took a LOT of abuse, but it finally stopped working last week.

I was going to replace it with a Fenix AAA LED light, but it is simply not nearly as bright, and I knew that was going to be an issue for my wife (the light provides a comfort factor when she'd walking out to the barn in the dark). So, I ordered a Fenix E15 single CR123A with a twist switch for about $27. I'll let you know what I think when it arrives.