Low Body Voltage Infrared Saunas

Matt, I don't understand this low body voltage stuff. Is this different than low emf? So confused, and want to buy a far infrared, as it's what I've been using and has been helping me significantly. Just don't want to get zapped, and want to buy a safe one that will last a long time. Any input? Thanks https://youtu.be/HvWErqynzyY