This was some old MDF I bought around 10-11 years ago and never used. Hard to say exactly what it is. This is the first time I've tried cutting through MDF. I was surprised at how hard it was. I also found it amusing that none of the sales force in any of the local hardware stores had no idea what to cut it with. One of them was an old-timer. Looked to be near 70 years old. He's the one that suggested the masonry cutting blade (which didn't work).