Hi Annie, for our Coachman 560   side bed. we went for a memory foam mattress, and went for a 9 inch  depth as aposed to the 6 inch   ( bigger is not always better)  it was another 10 kg heavier. And truly We don't think it would have been better.  6 inch mattress would have been better. ( any buyers).
	But a better mattress than the original.