Thin, light weight long-sleeve tee. I'm a 5'9" tall woman and I like the fit of the medium. The sleeves were long enough for me. I had my husband husband try it to get a man's perspective. He said the sleeves are too tight for him. The rest of the shirt fit well. So that being said, body is true-to-size, sleeves are more fitted. Nice lightweight tee. Good for layering. I found the neck hole on the medium a tad small/tight, where the large was more comfortable for me.