Body: 100% Recycled Polyester. Underarm: 100% Recycled Polyester Mesh. The resilience you can trust on the mountains. The short-sleeve Defend jersey tackles even the most extreme trails with strategically placed, abrasion-resistant zones to protect you and the fabric from wear and tear under harsh trail conditions. TruDri™ fabric wicks moisture away, providing dry wearing comfort, while mesh panels ensure targeted cooling.