Processing good fit mediocre, good P / L

I had already ordered the Felt Sleeve for MacBook Air 11 inch. There I was from the look, the functionality (the relatively thick felt protects not only against scratches, but also against shocks) and the price convinced.

Negatives: The fit - too big actually. The sleeve is stitched / sewn on the edges, so you give away on each side at least half a centimeter.

Note: Reading helps! :-)
I had this sleeve for my MacBook Pro Retina (!) Ordered 15 inches, unfortunately, I had changed the color to black, which is only available for the non-Retina 15-inch MacBook. The non-Retina MacBook Pro 15 is thicker / bigger than the Retina model. Consequently, it is much too big (!): 2cm left and right, and 3.5 cm up / down. Thus, it will not even fit in a briefcase. This could have been avoided if I had paid close attention when ordering, however, one could separate the color and size choice clear.