Imagine a jacket so light and warm you forget it's even on. The Fly Thermal W Jacket is just that jacket. From the inside out we constructed this jacket to be impossibly light and warm using Castelli FLY Fabric Technologies: FFT. First, we started with GORE-TEX INFINIUM™ WINDSTOPPER® as the lining. Its unparalleled performance keeps the wind from hitting your chest to keep you warm, but it also breathes and pushes the moisture from the inside out. Next, we found the lightest, warmest insulation that is 100% recycled material. CLIMA SL insulation not only insulates but breathes as well. Finally, the FLY SL shell is again made from 100% recycled material that blocks the wind and is treated to shed water and protect you from light rain and road spray should you get caught out in a quick rain shower. We've also added a packable hood to the jacket for extra warmth. It easily unrolls when you need it with a quick velcro tab to open up, either when the temps drop or you stop during the ride. It fits snuggly under the helmet to keep any unwanted air out. Like any good jacket, it's finished off with a YKK® Vislon® zipper, three back pockets that offer plenty of storage along with a fourth zippered pocket for valuables, an elastic with silicone gripper at the bottom to keep the jacket in place, and reflective tabs for added safety while out on the road. This is our next step in creating an environmentally friendly jacket that performs how you'd expect a Castelli jacket to perform.