When ordering a frame you will get a frame one size up to the print size to make space for the passepartout. For example: 21x30cm print with frame becomes 30x40 in size, and 50x70cm becomes 70x100cm. When buying a frame you always get a passepartout.
21x30cm = 30x40cm framed
30x40cm = 40x50cm framed
50x70cm = 70x100 framed
70x100 prints are not available framed.