The Whoop 3.0 Accessory Battery Pack with USB Cable is a black plastic accessory designed for the Whoop 3.0 activity tracker. It features a 1920 x 1080 display resolution and provides both decimal and imperial measurement systems. The battery pack is powered by batteries and includes an optical bio-tracking sensor for measuring heart rate. It is suitable for indoor and outdoor use, with a focus on running and jogging activities. The accessory is compatible with Android operating systems and is designed for unisex adults to wear on the wrist. Made by the brand Whoop, this accessory is an essential component for tracking and monitoring physical activity.