RiteCo 15201 Posterboard/Railroad Board, 4-Ply, 22" x 28", White (Pack of 25) Go to amazon.com Related posts Where to find poster board? Feature4-ply Poster boardWhite22"x28" sheets25 Sheets per cartonBoards are excellent for posters, project mounting, matting, block printing and a variety of craft projects DescriptionRiteCo, Poster board/Railroad Board, 4-ply, 22"x28", 25 Sheets, White.