vpr555arozzi rep has answered this few posted below as I asked this same question. he stated its MDF. or as I call it pressboard. fairly certain the easiest way to picture it is its sawdust and a binding agent (glue) , set under very high pressure. . but perhaps rep will have a different take on it.
oh almost forgot the mdf has a black laminate on both top and bottom. each of the three sections that make of the desktop have a fairly large hole just behind the mounting frame. the mat then has basically a big x cut over each hole.
what has got me to thinking the most today is the mat itself, wonder how easy/hard it is to spot clean in place? yes I know its says its removable and washable but can't see myself taking out all the routed wires to wash this in a machine. plus if the edge stitching is going to fray its going to be when its getting washed.
still pretty much undecided on the desk purchase. guess I have two days to figure it out.
vpr555It is MDF. You do not need or want hardboard for a product like this and, working with natural wood in China is very difficult because of import restrictions on wood products from Asia. The legs, feet and support braces are steel. The unit weighs 85 lbs and the shipping weight is 104.5 lbs.