Finnmark FD-4 Trinity Infrared & Steam Sauna Combo Home Sauna with Infrared & Traditional HeaterFinnmark FD 4 Trinity Infrared & Steam Sauna Combo Home Sauna with Infrared & Traditional Heater The Trinity Combination Sauna is the only sauna available that combines Finnmark's UL listed Spectrum Plus infrared heaters combined with a traditional 120V sauna heater, plus true medical grade Spectrum Red Light Therapy. No need to compromise. Finnmark's FD 4 Trinity is the only combination sauna with true UL listed infrared heaters together with a