A modern furo may be made of acrylic, and the top of the range models fitted with a re-circulation system (oidaki) which filters and re-heats the water. This system is connected with the hot water heater, either gas/propane fired or electric/heat-pump types. Luxury models are still made out of traditional or expensive woods like hinoki, and can be retrofitted with Western-style fittings and used as signature pieces by architects and interior designers internationally.