Hydro Foam™ is a layer of third-generation memory foam infused with a unique thermoregulating gel to keep sleep fresh and comfortable ALL year round. The open cell ‘cooling’ technology counteracts the natural heat retention of memory foam, using tiny heat-sensitive capsules that react to your body temperature. The carefully engineered foam provides orthopaedic support, keeping your neck, back and spine in perfect alignment while you sleep. All the benefits of memory foam combined with optimum breathability and airflow to have you drifting off for a fresh, restorative sleep, night after night.