With layers of blended British wool and viscose , home-grown hemp and crisp cooling cotton. The Corsica has 9000 innovative springs; including 100% recyclable advanced Cortec™ Revolution pocket springs and pressure relieving HD 4000 micro springs. With an in-house woven FR chemical free mattress cover and two rows of side stitching, this Seasonal Turn mattress has a warming wool winter side and cooling cotton summer side.