The WHOOP 5.0 sensor is a small, lightweight wearable device that tracks various physiological metrics to provide insights into sleep, strain, recovery, and overall health. It's designed to be comfortable for 24/7 wear and can be worn on the wrist, bicep, or with WHOOP Body apparel. The sensor uses advanced optical sensors and an accelerometer to measure heart rate, heart rate variability, sleep stages, movement, and more