I spoke to a rep from Rocky Mountain Mattress yesterday and confirmed that their poly foam base layer is 1.8 lb density. I think the 2.5 is a reference to some sort of scale that they donāt go into enough detail about on their website. I think the RMM mattresses with the 5 lb memory foam are still one of the better options for heavier folks, as the 1.8 poly foam base is the only suspect link. With companies like Novosbed and Foamorder moving away from 5 lb memory foam to lower densities, itās good to see that RMM remains an option for folks with a little more body weight than the average individual.