These are the highest quality boards found anywhere! At 35 pt, these are 46% thicker as 24 pt regular backing boards! Made from 100% acid-free, virgin wood, cellular fiber, 35 pt. thick cardboard. Contains a 3% alkaline buffer and a pH content of 8.0-8.5. Sold in packs of 50; Measures 7" x 10 1/2".