Very lightweight windproof microfibre front fabric. The sides and back sleeves are made of elastic mesh stripes to prevent the fabric from fluttering in the wind. Folds into an extremely small space. Back pocket YKK Vislon zip Reflective piping NEVER YOUR OLD STYLE WINDPROOF JACKET AGAIN. This jacket is an incredibly lightweight layer that does not let the wind through in front of you, allowing ample breathability thanks to the mesh side panels. But what you'll really appreciate is how the stretch panels on the back of the sleeves were used to ensure that this jacket is worn like a second skin: no fluttering fabric, no fresh air circulating inside the jacket. This jacket is light and warm enough to be worn throughout your ride in mild conditions, but if you want to take it off, it fits perfectly into a back side pocket and takes up minimal space in your back pocket or under saddle bag.