We will never use gels in our Memory Foam (Visco Elastic), they restrict air flow and can make you sleep hotter. Airflow is the key to cool sleep. We will never use waterproof membranes. We all sweat to some extent, the average is 200 millilitres per night, when we sleep and the waterproof membranes trap … Continue reading What materials are not used in the 624 mattress?