Stopped by the recycled building materials store to see if they had anything for my hearth build. Lo and behold sitting in the back of the store were some dismantled cubicle partitions. Told the guy I didn't need the frames and asked what he wanted for the boards. $5.00. They have material glued on them which will have to be peeled of but the Micore 300 stamp is on the back. This stuff was nowhere to be had in Idaho. I called every USG distributor. I had no idea what this stuff looked like, if it had not been for the stamp on it I would have mistaken it for cheap particle board made with newspaper. Just a hint for anyone that finds it this way. Not every board had the stamp on it. So if there was nothing to compare it to you could pass it by.