The 13 inch mac book pro has an active cooling system. That active cooling system is important in a particular set of use cases and work loads, where it's a more sustained performance that you need to have. The mackbook air is going to be phenomenal for people who are looking for an amazing, amazingly capable and versatile machine. And so it's its subtle, but i do think there is a place where a pro user is going to feel more confidence with that mac.