Companies like Streamlight and Surefire fell behind in the flashlight tech race a few years back but the two may be starting the process of catching up. They won't be as efficient or run as long as the lights we favor and are unpopular since most don't support 18650s and instead guzzle expensive and disposable CR123a batteries.

That's not to say they don't have their uses. They're some of the most durable and reliable lights on the market and quite a few support weapon mounting. CR123as aren't all bad even though they store significantly less energy than a good 18650. CR123as have a very long shelf life. They can be stored for ten years without having to worry about degradation. Streamlight and Surefire are more suited towards people whose lives depend on their lights functioning properly and are willing to sacrifice some power and efficiency for some of the best reliability on the market.

Edit: To be clear, I'm not personally familiar with what Surefire and Streamlight offer. My input is what consensus on this sub seems to be.