Michael Zendelwrote a review of Castelli Flanders Warm Long-Sleeve Baselayer - Men's on December 12, 2017
Familiarity: I've used it several times
I needed another base layer to stay warm on cold weather rides in the NY area. It's a little on the small side (which is expected for Castelli), but stretches very comfortably. It fits very snug, but is not tight. I rode in mid 40's and mid 30's, and it definitely keeps me warm. It's probably too warm above the mid 40's, but perfect for anything colder. The shirt was completely soaked in sweat after my ride, but I did not notice any dampness during the ride.