I bought this for my 6'1", 250lb, 24 year old son; size xl-red. He got a real kick out of it. The material is good quality. What you would expect from L.L. Bean.
My husband laughed when he opened his Christmas gift and saw this. It's a great gift idea! Order your normal t-shirt size as a good estimate for wearing as pajamas, it tends to run large. Although if you plan to wear it under clothes to stay warm during the winter months (awesome for snowboarding), order a size down.
This is not designed for slim men. My husband is a trim 56 year old and the size small had way too much belly room. The extra fabric made it difficult to wear comfortably under other clothes.
The material was high quality and the garment well made, but definitely not suitable for an athletic build. Returning for a refund.