These AAAA Ultralast batteries do not have the little bump on the positive end as you would expect in a AA, AAA, or any other battery.The positive end is almost completely flat. Strangely, the negative end has a weird counter-sunk hole with a bump in it, but that bump does not extend past the end of the battery.As a result, the stack of 3 of these batteries is just over 1/8" shorter than a stack of normal-looking Energizer AAAAs. The button on the flashlight does not go down far enough to connect, and it won't turn on.