Features: Adjustable elastic band, rear warning lights, adjustable brightness settings for front chest lamp and completely waterproof. Outdoor: Train safely and illuminate your path with this highly visible chest lamp. Chest lamp : Get an outdoor sports chest lamp. Durable: Up to 15 hours from one 2-3 hour charge! (3.5-4 hours approx. under strong light, 8 hours approx. under low light and 15 hours approx. with flash).