The front of the Aria Undershirt Gilet is completely windproof, preventing any loss of warmth via windchill. Meanwhile, the Striped mesh back fabric provides outstanding breathability so you don't get too hot and sweaty. And both materials are super-light, creating a undershirt coming in at 75g, meaning you'll barely feel the undershirt once it's on. However, it's not just the core windproof protection you'll love. The fit is brilliant too. Gone is a flappy, loose garment and in its place is a streamlined and stretchy fit that won't slow you down when cycling. Thanks to the stretch you still enjoy full mobility too. And when you're ready to take it off, it folds into its own pack pocket, taking up minimal space in your jersey pocket.