Barrel Diameter: 2 1/4", Bristle Diameter: 3". The ProThermal Anti-Static Collection by Olivia Garden boasts a new design with new technology that's better than ever. The Vented Cap Design keeps top of brush head cool, boosts ventilation for faster drying and the lighter brush design makes styling easy. Greater Airflow from increased hole size reduces drying time and improves styling results. It has a heat-conductive surface and anti-static, high heat resistant bristles. Ergonomic Design makes the brush extremely lightweight and easy to rotate. It is perfectly balanced to reduce wrist fatigue and has a "Sure Grip" non-slippery, snag-free seamless handle. Includes a patented retractable sectioning pick.