"What is that?" lit up our social media channels when Tao Geoghegan Hart wore a prototype of this base layer up and over the Stelvio on his way to winning the 2020 Giro d'Italia. Those conditions highlight where this piece excels: it provides a surprising amount of warmth by pulling moisture away from the body, keeping you warm always, but the mesh construction means it's not too hot. Great under a jersey for high intensity, or for layering under a jacket.