be sure they works well and dont watch them as a toy ,if they applied on a man with heart disease or if they applied in the sensitive body areas ,such as neck ,chest,..., you certainly will have a serious problem.these circuits use some diodes and capacitor as clamper circuits which is similar to the high voltage stage of crt tv's and monitors.as you know the voltage behind the crt is about 15000v~20000V depending on the crt specifications which of course is large voltage and can shock seriously.
Oh my... and I thought you say we could not increase wattage (work force) from a battery source

Oh my, battery must be dangerous ... HAHAHAHA
Seriously,
Here is an example where wattage being increased.
Low energy continuous power from a battery is transformed into short pulses of HIGH energy.
QED