Prices include 3.5 cm wide authentic solid wood handmade frame, matted and normal glass.  The prices given are given according to the passe-partout glass size of the frame, it is the inner size of the frame.
Example: For your 20x30 cm product, look at the 30x40 cm size in the list for this model frame with 5 cm mats, 30x40 cm is the inner size of the frame, the finished version will be 36x46 cm. Likewise, if you are considering 7 cm mats for your 30x30 cm product, look at the price of 44x44 cm, 45x45 cm.