This adidas smart bra features exclusive heart rate sensing technology knit directly into the fabric, no chest strap required. Knit-in heart rate sensing fabric accurately and comfortably captures heart rate data during your workout. Use with adidas heart rate monitor pod and Train & Run app to get heart rate coaching and reach your fitness goals. Smart Bra features seamless technology and double-layer construction to deliver a second-skin fit for reduced chafing Compatible with snap-on transmitters from other technology brands, e.g. Polar, Garmin, Runtastic, Wahoo Fitness, Zephyr, etc.