50 pcs*A3(297mm x 420mm;11.7*16.6 inch)transparent&clear background color inkjet water slide decal paper|water color paper|paper colorpaper transparent - AliExpress
Amazon.com - A3 - (297 mm x 420 mm) or 11 3/4 x 16 9/16 in Poster Frame (Derby) European Size Picture Frame -
Paper size A0, A1,A2, A3, A4, A5 - To understand everything about the different paper sizes