I have a Tank 007 TK-566 1 mode that is often my every day carry with a 3.7 Volt 14500 battery in it. Nice and bright, compact, well made, strong throw, nice spill. I also have the TK-566 5 mode, and I got the extension so I can run it on two AA batteries.(I havent tried this with the 3.7 Volt battery) I gave these out, with the extenders, to the guys in my family for Christmas. It's nice to be able to run this with standard AA batteries. I also have the TK-360 using a CR123 battery. My Tank 007 lights are well made, smooth, with a nice beam, no rings, good throw, and reliable. I would recommend Tank lights to anyone.