Yeppers it tizz MDF and the cabinets are fully enclosed, I will be cutting out the openings for the two top mounted vent fans in the racks today.. I usually use oak ply but because of the dimensions of the racks there was going to be considerable waste, and at HD cost of $ 54 per sheet there is about a $ 22 per sheet savings by going with MDF and just laminate oak skin over it. A bit more labor intensive offset with the advantage of having a better looking finish when done becasue the oak skins have a much tighter grain than oak ply.

With no longer having room for a nice cabinet grade table saw and just using straight edges and a skill saw for cutting sheet goods, the MDF is nice to work with and has the 49" x 97" dimension. First time I have seen this available in HD, its a special size used mostly by cabinet shops. Actually had a good day yesterday as once the cabinets were finished, the dimensions of each were within 1/64"of each other and perfectly square, which was critical for the racks as I don't want more than about 1/8" distance from the rack rail to the finish trim on the opening.................so I screwed up some how. lol