On started with running. And now, they're going back to their roots. This is the Core-T. The lightweight option for everyday runners who want to stay fit. Featuring one fabric in a stripped-down design, it's the wardrobe classic that performs. Fit & Design: With its lightweight fabric, it's a closet staple that won't slow you down A stripped down design, in one color, to complement any outfit Developed with the planet in mind, it's made of 92% recycled polyester