Your body changes every day and now the comfort level of your mattress can too! Sleep Science designed a mattress for sleepers that need medium-soft one day and medium-firm the next! Simply flip the mattress over for a restful night’s sleep. Each side of the mattress is easily identified by a color-coded cover that is also simple to unzip and wash as needed! When the light blue stripe is on top, the medium-soft side is on top. When the dark blue strip is on top, the medium-firm side is on top.