New favorite light jacket for running around town, a crisp cold fall walk, or for putting on after a sweaty gym session! I am very happy with the Medium!! If it helps... I am a 34DD so I don’t like jackets to be too tight around my chest, the medium is perfect and the arms are not long at all! I’m 5’3” (short torso, small waist). Just enough room to be comfy, long enough, and not too firm fitting!