This is an excellent hack when you need to replace AAA batteries, but when you need AAAA batteries,there are more differences between these cells and store bought AAAA cells; 1) The polarity is reversed so that the negative terminal is the one with the little "Button" on it, 2) that little button doesn't protrude as much as on a store bought cell, and 3) the hacked cells are just a tiny bit shorter than their expesnsive counterparts. My Streamlight Stylus LED flashlight won't work with these cells. I think that it requires the positive terminal to protrude into the LED assembly. I tried to remove the "button" from and old AAAA battery so that I could use it to extend the flat positive end, but I was unsuccessful. Does anybody have any suggestions that would make these AAAA batteries more functional? Thanks, Matt