Acid-Free Foam Board (1/8in) for Mount and Backing of Photography
20" x 30" Acid Free Foam Boards, 2ct. | Michaels
Acid Free Foam Core
Amazon.com: Jerry's Artarama Acid-Free Foam Board Sheets for Artists and Framers 20"×30" (1/8" Thick), Box of 40 - Ideal for Mounting and Cutting, White Foam Poster Board, Foam Core Board - White :