Bought this back 4 months ago.. It was 17" depth but wished I got it bigger.. It comfortable but the more you sleep on and  it does flatter so had to rotate the mattress and felt better... But it is hard to turn yourself in a comfortable position.. Also for flat sheet on it is ok but it moved and it annoying but please I recommend to buy as it so comfortable and warm as well.. Don't let the things that will happen but it so comfortable I would not change a thing