Most of the infrared saunas that are on the market are made in China. The suppliers/distributors that you will encounter in the US obtain their saunas from these manufacturers in China and just relabel it as their own including trying to differentiate their heaters by implying it is a special, exclusive technology. This is almost never the case, just a way to lure customers into spending more money.
Watch out for: some sauna resellers will advertise a 2-person or 3-person sauna at an unbelievably low price; however, the sauna dimension is far smaller than the recommended size. You need to know the difference between a decent sauna and the cheap replica, so be aware.