COMFORT FOR COMPETITION. The Nike Dri-FIT Park 7 JBY Jersey features smooth, sweat-wicking fabric with mesh on the back to help keep you dry, so you can stay focused from the opening whistle to the 90th minute. This product is made with at least 75% recycled polyester fibers. Dri-FIT technology helps keep you dry and comfortable. Mesh panel on the back adds breathability.