Keep track of your heart rate and maximize your workouts with this Polar RS300X SD Heart Rate Monitor. The sleek design in black color complements any gym attire and the wide range of features like average heart rate, gym and training tracking, and running performance metrics make it an essential fitness tech for any athlete. The model is RS300X and the brand is Polar, a trusted name in the fitness industry. This heart rate monitor is ideal for fitness, running, and yoga enthusiasts who want to take their workouts to the next level. It comes in a new, unopened box but requires a new battery to get started. Use it to track your progress, set new goals, and push yourself to achieve more in your fitness journey. battery type CR2025