Replacement Li-Ion Battery - USB-320 Series

Amazon Review - Proper. Battery for my flashlight.

As far as apearence goes, it looks exactly like the picture does. A battery that looks like a battery. Once it arrived I charged it for a few hours and then installed in in my Nightstick TAC-540XL. There was a review on here that stated it did not work with this unit, and at first this is true. For those individuals using the included CR123 battery cradel with their flashlight, you have to take a pair of needlenose pliers and GENTLY decompress the springs on either side of the battery housing. After some trial and error, you will find the proper spring length and this battery WILL function in your 540 unit.

However, I do not know how the rechargiable unit compares to 2 CR123 batteries as far as powere output is concerned. I have not checked with a voltimeter yet.