It's tempting to ditch every extra layer as soon as the sun comes out and late spring officially takes hold, but riding with a baselayer can still make a big difference in temperature management and breathability. On a warm spring morning with a cool breeze, layer the Castelli Pro Mesh Sleeveless Baselayer under your jersey. Rather than being weighed down by the extra layer, you'll enjoy faster moisture transfer with the addition of ultralight mesh fabric next to your skin, helping you stay drier as you heat up in variable temps.