Yes as far as that goes I believe the back panel is MDF, as for attachment I had these speakers back over at Earl's about a month ago to remeasure and do frequency sweeps on them after a couple months of play time on them. We opened up one of the speakers and that back panel is extremely secure and sealed very well onto the Poly cabinet, and the crossover is a thing of beauty, sorry no pics of that, you'll have to buy your own pair to see that.
Dan