Natural and patented, the 'Warm Diffuser System' technology was developed by Babymoov. The heat diffuser is made from organic matter peat. Place the heat diffuser in an 800W microwave or in hot water for 5 mins. It's ready! Really practical, the heat diffuser fits in the bottom of the bathtub (compartment provided). The Aquanest heat diffuser maintains your baby's bathwater at 37°C for 10 mins."