My boss is interested in some of my local (USA) landscapes. He's looking for prints that he can easily carry back and have framed in Norway. I hope someone can provide readily available European frame and mat sizes corresponding to US 8x10 inch, 11x14 anf 16x20. A3 and A4 don't mean much to me. I'd appreciate knowing outer mat and window dimensions in centimeters (or centimetres), if you could, please. Thanks.