I installed the Froli system in V-berth and aft cabin
with high quality foam mattresses and a 2" foam topper pad. Very comfortable and much cheaper than a custom-buillt inner-spring mattress. I have no stake in the company, just a satisfied customer. Because they create "breathing" space between the bunk surface and bottom side of the mattress, there's no condensation
, another benefit. Their website is frolisleepsystems.com.
Grebe, Valiant 40