Many people think that all 9 volt batteries are the same. Not true. Low quality batteries are not strong enough to power stun guns. Some 9-volt batteries are even too big in size to fit into our stun gun battery compartment.
Stun guns produce electricity as their main purpose. It stands to reason that the source of that electricity come from a strong origin. The brand we and the manufacturer recommend is Eveready Energizer™ These 9-volt batteries have sufficient juice to power our previous generation stun guns. Off brand and especially non alkaline types are not made strong enough for the requirements of a stun device.
We've seen some 9 volt batteries stuck inside a battery compartment because the size of the battery was not a standard sized 9v such as Energizer's. If you try to put batteries in a compartment and they do not fit, do not try to shove them in there. They do not fit.