100 Sheet Music Size Backing Boards / Backers (9-1/4" x 12-1/8") - Protect Sheet Music From Bending! #MAIWSH These boards will help protect your larger sheet music pages from bending in their bags in storage! 10 1/4 X 12 1/8 (234.95mm x 307.98mm) Buffered with 3% calcium carbonate Coated on one side