During a triathlon, you need complete freedom of movement, aero and hydro dynamics, and muscle support. The Castelli Free Tri Top uses two strategically placed fabrics to achieve peak performance during the run, on the bike, or in the water. The front panel is made with Instadry hydrophobic fabric. The tight knit composition provides muscle support to neutralized the effects of road vibration and shock. The next to skin fit won't increase your drag in the water or on the bike, and the hydrophobic treatment provides a smooth surface to help you glide through the water. It also dries quickly, so you won't be weighed down when you leave the water. The back panel is made with Castelli's Velocity mesh. This material promotes airflow to keep you cool. It also manages moisture by moving it away from the skin to the surface of the fabric to evaporate. Flatlock stitching is used throughout the Free's construction to reduce chafing. Micro clip hooks hold the top in place during the swim and bike legs of the race. Two slim, side entry pockets at the back of the jersey are virtually invisible to wind and water, but easily carry arm warmers, a vest, or nutrition items.