I am 5'4.5" 135# with an athletic build and the medium fit perfectly. I have broad shoulders and found no restrictions regarding fit or arm hole size and I groom and saddle my horses, so I would not be pleased if there was a poor fit. I like the weight (which I consider mid-weight) to fill a wardrobe gap as my 900 weight vest is often too warm. My vest is grey heather and I also purchased a grey EB fleece, both on sale. I found both to be a great value and I am so happy with them.