I’m 5’4, 120lb, pear body shape. I tried size small and size medium, size small is tight on my armpits, however the sleeves on size medium are way too long for me. Considering I need to use my Garmin watch to track heart rate consistently during running, I decided to keep size small. Merino wool is soft, light yet warm, I would wear this shirt when the temperature is 55-60 Fahrenheit. The cuffs on the shirt are tight so they prevent cold air getting under the shirt. Like other tracksmith clothing, there are no tags or wash labels on it, which avoids friction during running. The colors of Brighton base layer are pretty low key, they would look cute with any color shorts. They would look good with jeans/lululemon casual pants as well.