The Lost Coast Long Sleeve Reflective T1 Jersey incorporates our lightweight thermal fabric in a race-fit construction. Not only did we add a thermal fabric, but also strategically inserted reflective and mesh paneling for visibility and ventilation. Our new thermal rating system T1, T2, and T3 designate insulation and comfort ratings based on the fabric. T1 is our lightest weight thermal fabric and is suggested for temperatures above 50F. With a Pismo Base Layer and vest, you can brave temperatures in the 40Fs.