Ordered a Large because mediums were out of stock, but I'm glad I didn't because a Large fits nicely. The jacket is nice and snug, rather comfortable, even in warm conditions. The material inside and out is nice and lacks any bit of irritation. Love the pockets and arm pouch with mounts for pens. A little saddened by the lack of names on some of the shuttle patches, however. They do look nice, but lack some of the most important details of some of those missions. On top of that, some of the stitching on a few are already loose. Small things for a big cost to boot. But nevertheless, it is a very nice jacket covered in some of NASA's history, and I'll be wearing for as long as it'll stay together.