- Size: One size • Made with 15% spandex and 85% polyester, this undershirt is soft, comfortable, durable, and lightweight. • Provides maximum breathability to keep you cool and dry during your bike rides. • Ergonomic design with stretch fabric that adapts to your movements while pedaling. • Fabric with square holes that promotes heat dissipation and quick drying. • Ideal for road cycling and MTB, as well as running, gym, and daily exercise. • Check our size guide before making your purchase.