The GNC Fitness Heart Rate Monitor & Sensor Band is a versatile set designed for indoor and outdoor fitness activities. It includes a wrist sensor band, watch, and bike mount, all powered by batteries. The heart rate monitor provides accurate measurements of heart rate, time, and calories, making it perfect for gym and training sessions. With its gray color and reliable sensors, this fitness technology from GNC is an essential tool for those looking to track their workout progress and improve their overall health and fitness.