Rechargeable Battery 3.7V 3600mAh for Streamlight X Series Flashlights 2-Pack (Red)

USB-C charging helps limit the number of cables I need, they fit perfect in my surefire flashlights and appear to last as long between charges. I picked up two of these for the price of one surefire comprable battery. I will see if they last as long or have issues in cold or hot weather but for now I am pleasantly surprised by these batteries.

These batteries are rated at 3600mAh. I have an analyzing battery charger and was able to measure 3408mAh on one of the batteries and 3256 on the other. Even though less than labeled by a bit, I still consider these as high capacity batteries. 3600 mAh is currently the upper possible limit on 18650 battery chemistry. The cells are protected with a built-in chip which I suspect is causing the batteries from achieving the full 3600 mAh. As an aside, note that there are far too many sellers of 18650 batteries that label the batteries with ridiculously high ratings (I've seen false claims of 50,000mAh- totally impossible, and when tested, actual capacity was extremely low.). Another feature of these batteries is that they can be recharged with simple micro-USB chargers - a big plus for most that don't have Li-Ion battery chargers.

Do not buy, Batteries are 90% of rated capacity, and complaint turned into Amazon without ANY response from the seller. That should say it all, I will have to return these!Update, returned, if you want an 18650 that is as advertised, "LCLEBM 3400mAh Flat Top 3.7V 20A Rechargeable Battery" They actually had 2 that tested higher than rated capacity!

These seem to be good batteries, and I like the USB-C charging design which even includes and LED to let you know it is charging or done charging. However, in my flashlight the length appears to cause some issues It will power the flashlight, but only when the battery cap is slightly untwisted -- but not too untwisted. In regular use this would be very challenging as it also flips between settings improperly with this battery installed.However, the batteries themselves are probably fine, I just can't use them. Wouldn't recommend if you are purchasing for your Streamlight HL-X.EDIT: I was able to get them working better, just requires twisting very tightly!

These are Chinese 18650 lithium ion rechargeable batteries that have a USB micro B port with an indicator light that lights up green when fully charged (red when low). Took about 5 to 6 hours to fully charge. These will not fit into a flash light that uses CR123 batteries because they are a little thicker than the CR123. They fit perfectly in my Pelican 7000 and Wowtac A1S. The Pelican 7000 uses two CR123 batteries inside of a plastic sleeve that makes it the same length and width as an 18650. Comes with two batteries and one plastic case. No charging cable included, which kind of sucks. Means you have to buy one if you don't already have one. Otherwise, not a bad deal.