Unlike an ordinary circular spring system, Miracoil's unique shape has twice as many springs offering improved pressure relief, edge-to-edge support for maximum sleep space, and zoned support right where you need it most. Featuring eco-comfort fibers, this mattress is good for you and good for the environment, as its comfort layer is made from 100% recyclable plastic bottles which offer breathability and enhanced comfort for a more refreshing night's sleep. Tried and tested Miracoil®'s spring system also has enhanced durability providing superior comfort over many years. No roll together ensures less partner disturbance Targeted support zones for superior spinal alignment This is a single-sided mattress - the filling layers are only on one side of the springs and should be rotated from head to toe - rather than flipped over. This is a very firm mattress due to the tufts and offers support and pressure relief. The double mattresses are tested up to a combined weight of 30 stone or 190.51 kg