Our mattress toppers were designed for being used on a flat mattress. Using a topper on a sofa bed, roll-away bed, foldable RV or boat mattress may damage the topper as the topper will be folded unnaturally for long periods of time. This may cause the foam to crack and will void your warranty. You may use the topper on these types of mattresses only if they remain in a flat position at all times.