What's the saying? Train smarter not harder? That's the idea behind the Impel Short Sleeve. The intelligent design behind this shirt helps you stay cooler by incorporating Polartec® Delta™ fabric that feels cool against the skin, thanks to its ingenious engineering. The fabric weave has elevated yarns that increase airflow, reduce friction against the skin, and regulate moisture management. The result is a shirt that works in unison with the body's cooling system to keep you more comfortable in hot conditions.