This product is made with at least 50% recycled polyester fabric. The material comes from plastic bottles that Nike has diverted from landfills since 2010 - bringing Nike's total to more than 6 billion. All-new recycled materials made of crimped yarn create airflow to help keep you cool. The soft feel helps cuts down on chafing during your long distance runs. The seams at the shoulders are rolled forward to help your arms move freely. An overlap vent at the back extends the coverage while also keeping you mobile.