I have manufactured and sold zappers for years. It is my experience that wrist straps are the least efficient electrode and those who use wrist straps are more likely to suffer burns (light skin burns).
The zapper can be very effective and some are effective enough to be considered as CLASS III devices by the FDA.
If your husband is not so narrow minded that he can not learn, get him a copy of parasite
Zapping and the Zapper.