Open Coil Memory Using a 13.5 gauge open coil spring system below a luxurious 25mm of memory foam, the open coil memory mattress promises comfort and relaxation every night, helping your body feel at ease - especially because of the price. There is also a steel rod edge that surrounds the sides of the British made mattress, which is used to minimize sagging along the sides and resulting in unwanted roll off. This popular spring system features interconnected springs that work in cohesion to provide fantastic total body support. Typically this system is cheaper than pocket springs mattresses, making this mattress a more affordable yet supportive and comfortable option. Medium firm sleeping surfaces are extremely versatile and work well for many sleepers.