Hi maskedrose,
I would guess that it would be the same 2 lb density polyfoam except more of it in thicker or more layers but I haven’t asked them so I’ll be interested in their reply … as well as your experience and feedback of course when you receive the mattress and have had the chance to sleep on it 
NOTE ADDED: For those that are reading this topic from the beginning you can read more about their new design that was launched in November, 2014 in posts #2 and #6 here and there are more comments and feedback about their new design it in post #205 and onwards in this topic
Phoenix