UCreate Poster Board, White 10pt, 22" x 28", 50 Sheets : Amazon.co.uk: Stationery & Office Supplies
Outus 30 Pcs 3/16inch Thick Foam Boards 22 x 28 Inch White Foam Core Backing Board 5 mm Foam Poster Board for Presentations School Signboards Arts and Crafts Framing Display : Amazon.co.uk:
Office Depot® Brand Poster Board, 22" x 28", White, Pack Of 10 - Zerbee