For those shoulder seasons rides where it's too cold for just a jersey and too hot for a full-blown jacket, the Castelli Fly Thermal Jacket is our go-to. Made with Castelli's Fly SL shell for rain and wind protection and insulated with CLIMA SL synthetic fill, the Fly Thermal Jacket is lightweight, warm, and comfortable. A GORE-TEX WINDSTOPPER inner lining adds even more warmth and comfort and blocks out all wind from spoiling our warmth. Three rear pockets and a zippered security pocket allow us to store all our essentials close to the body, and an elastic hem with a silicone gripper helps keep the Fly Thermal Jacket Fly Thermal Jacket in place.