Trifold Poster Board 36″ X 48″ White Presentation Board Science | eBay
Amazon.com : Two Cool Tri-Fold Poster Board, 36 X 48, White/white, 6/carton By: Eco Brites : Office Products
Elmer's 36" X 48" Tri-fold Foam Presentation Board - White : Target
Amazon.com : Trifold Poster Board 36" x 48" White Presentation Board Science Fair Display Boards - for School, Fun Projects and Business Presentations - by Emraw : Office Products