Hi swapgut,
There is more information about the Original Mattress Factory (OMF) Serenity with the correct specs and some comparisons with other latex and latex hybrid mattresses in post #8 here and the other posts it links to that should be helpful 
The comfort layers are blended Talalay which is a very high quality and durable material and the middle polyfoam core is 2.5 lb polyfoam which is a high quality/density version of polyfoam and it’s also two sided so there are no “weak links” in the mattress.
Phoenix