The Natural Rubber mattress uses a 6-inch core of Medium-Firm Natural Rubber that provides pressure point relieving support. Surrounded with quilted layers of wool and cotton and encased in an organic cotton fabric, the Medium Natural Rubber mattress is extremely durable and resilient. The Organic Slat Foundation provides perfect support and unmatched comfort for the Natural Rubber Mattress. It's solid wood slats are of fitted following traditional European design and covered in a heavy-duty organic cotton fabric.