I do not know many people who can benefit from KV,
The KV is done with an ordinary 4,5V battery on a choke (220V small transformer coil) by cutting the battery current manually, and a power LED. will not resist over a hundred microseconds !!
Basic assembly to make my children feel safe but informative about why we do not play with the 220V, (and also in a concrete course on the induction law, better assimilated as well) but also good an electric fence !!