Postcard for the holy days

Yesterday, i finally completed a postcard for the upcoming holidays / winter days / christmas days.
it took me a while, i'm surprised by my own patience to draw again and again and again the same mittens. This is the result..

I doubted a while about the size, i think it actually was perfect size 120x120 (square)... But it's much more expensive for mail (you need special envelopes), so i kept the regular postcard-format. 
Do you think it's good to take this into account? 

The cards are in print now
(and for those interested, available from saturday!)