These look ok but the thickness was too thin being 3.5 inches instead of 4 so I asked if they had 5 inch thickness which would've been 4.5 inches and fit my furnace much better, they indicated they didn't make them that size which was disappointing seeing they made the 5 inch thickness in other sizes but not 25x25. So I'm stuck with a couple that are about an inch too thin.
I would not recommend nor would I buy these again. I had issues with one which they handled since it came massively damaged. The issue is the others are not made well. You are honestly getting what you pay for here. Spend a bit more and get the good ones