All eve mattresses work at their best one side up, so you don’t have to flip them over. They do like it if you give them a quick rotate, though. You can do this by picking them up by the stitched-in handles on the side or underneath, then swizzling them round by 180 degrees. Do that every 30 days for the first year then twice a year after that and you’ll have yourself an evenly worn mattress.