E.gerber 100 Half-backs Standard Comic Size - 7&rdquo; X 10-1/2&rdquo; These are the highest quality boards found anywhere! At 24-Mil, these backing boards ensure extra rigidity and protection! Made from 100% acid-free, virgin wood, cellular fiber, 24 mil. thick cardboard. Contains a 3% alkaline buffer and a pH content of 8.0-8.5. Sold in packs of 100 and measures 7" x 10 1/2".