I purchased one of these to have as a spare for my Nitecore P23i that I ordered recently. I always like to have a spare battery for my torch, as I can almost exhausted a battery with my usage (which is typically wildlife spotting down my local river and surrounding area). I have been very surprised at the performance of this battery in my P23i. I tend to use turbo/3000 lumens on my P23i quite a bit, which obviously has an impact on the battery. Despite my quite a bit of usage on turbo, the battery usually lasts me for the duration of my wildlife spotting, and usually the LED on the P23i has just started to flash rapidly (indicating less than 10 percent battery remaining) shortly before I am setting back off on my walk home. I find this absolutely amazing considering the insane amount of light/brightness that the P23i kicks out on turbo, and all this on just the one battery. Nitecore certainly do make some excellent batteries, and I have always been impressed at any of the other Nitecore batteries I have purchased. Some people complain about manufacturers using proprietary batteries (which these NL2150HPi batteries are). But using the dual positive and negative terminals on each end, has give them this amazing performance, and light output, and also battery life on just the one battery with their torches. Personally proprietary batteries do not bother me, when they provide excellent performance, excellent output, and excellent battery life. All in all an excellent battery again from Nitecore, and I am sure it will surprise and impress you with its performance.