With layers of blended British wool and viscose, a British wool, hemp and flax blend and a cotton, hemp and flax blend. The Emerald mattress has a 16500 Cortec™ Quad spring system, contouring HD 2000 Micro and HD 2500 Micro springs and Posturfil pocket springs. With an in-house woven FR chemical treatment-free mattress cover and three rows of side stitching, this Seasonal Turn mattress has a warming wool winter side and cooling cotton summer side. British Wool & Viscose Blend, British Wool, Hemp & Flax Blend, Cotton, Hemp & Flax Blend, HD 2000 Micro Springs, HD 2500 Micro Springs, Posturfil Pocket Springs, Cortec™ Quad Pocket Springs