This Pearl Izumi barrier jacket allows me to ride with two thin layers underneath in winter, from 18 degrees to over 30 degrees. If you ride in spring or fall, the t-shirt compression is all you need underneath. I washed it with Nikawax which further increased the wind and rain protection. Some reviews mention a zipper which, as the jacket is thin and very light, doesn't allow for a strong zipper. I've been wearing this for three years now, and being aware of the fragility of lightning I always