A breathable wave circular Knit cover has been designed to encapsulated this unique 3-layer mattress system. The top features plush REM-air memory foam that welcome your body and mind, meeting each pressure point with the touch of plush, contouring memory foam. The, the transitional middle layer poly foam bridges the top plush and bottom firm layers, catching the body as it contours lower. Finally, the unsung secret of hi-response poly base foam supports the body at its deepest points, helping support deeper REM sleep.