Natural Fillings are the most traditional type of mattress filling. These are heat-free and breathable and as a result, they ensure you have a cool and fresh night’s sleep. If you like a nice traditional mattress with a luxury feel, these mattresses contain wool, silk, cashmere, cotton, bamboo, tree silk or alpaca. The Hilary Devey Diamond and Diamond-Luxe mattresses feature a winter and summer side. The winter sides have a layer of wool on top, therefore, giving a warmer more snuggly feel. The summer sides are topped with cotton as a result giving a cooler feel for the warmer weather.