Whoop 4.0 Fitness tracker. Tracks recovery,sleep,heart rate, & overall fitness performance accurately througout the day. It is perfect for gym,sports, running and overall health monitoring.
NOTE: You'll need to create your own WHOOP account and Purchase your OWN subscription/membership to use the device and access the app features.
Note: For the chargers you'll need to replace them since they dont hold power for very long.