M-Line Slow Motion 4 mattress is 22 cm thick and has different layers. The new top layer consists of firm visco elastic foam. Primary support of this M-Line mattress is provided by the openstructure solid HR-foam. The nothes in the top layer differ by each zone. The pressure is well distributed throughout the body. Fiber of the Eco friendly cover is made of the eucalyptus tree. This matress is more firm than slow motion 3.