This is a brand new, unisex chest strap heart rate monitor module from Under Armour's Armour 39 line. It is designed to accurately measure your heart rate during workouts and provide performance feedback. The module is compatible with the Armour 39 app, which allows you to track your progress and set goals. With its sleek design and reliable performance, this heart rate monitor module is the perfect addition to any fitness routine. Whether you're a seasoned athlete or just starting out, the Armour 39 is an essential tool for achieving your fitness goals.