A4 A3 WHITE CARD SMOOTH CRAFT PAPER PRINTER THICK MEDIUM THIN REAM GSM CARDBOARD
Especially with 250gsm and 300 gsm, which are quite a stiff cards. CIE Whiteness (ISO 11475) - 145%. GSM is the weight of the paper, not the thickness. A3 297mm x 420mm (11.7" x 16.5"). A4 210mm x 297mm (8.3" x 11.7").