I replaced the battery on my Air with one from NewerTech and it was very pretty easy. The battery I ordered (from Other World Computing) came with the necessary tools too. It was just a set of tiny pentalobe screws on the outside, a few on the inside and then carefully prying up the battery connector to disconnect it. All in all, took about 20 minutes max, plus a few more hours for the battery charge/discharge they recommend at the beginning.