Vívofit jr. 3 isn’t just a fitness tracker for kids. It’s an interactive experience where your child’s activity unlocks exciting Marvel Avengers app adventures. This durable fitness tracker is swim friendly, perfect for your kid’s enchanted adventures. No need to stop the fun for charging. This easy-to-replace battery lasts up to 1 year. Let your child relive the Infinity Saga. Playtime unlocks Marvel Avengers adventures, games and icons.