I am not sure if the heart rate monitor fully works properly. It doesn't show up on my list of possible Bluetooth connections, and the only app I was able to pair it with was Strava. You may be able to attach a Polar or Wahoo sensor to the bra instead if the snap locations match up (but I don't know if they do or don't though,so don't take my word for it ).
Why use a heart rate monitor? Using tech to track your ticker
Amazfit W2215US1N Bip 5 Smart Watch with Ultra Large Screen, Bluetooth Calling, Alexa Built-in, GPS Tracking, 10-Day Long Battery Life, Health Fitness Tracker with Heart Rate, Blood Oxygen Monitoring - Black
Attachment pants (other) gray - Gem
Mi Pulse Smart Bras : Sports Bras with Integrated Heart Rate Tracking – Mi Pulse
Nicole at Home: Tutorial: Heart rate monitor-sports bra sewing hack
For Mi Band 5 Smart Watch Men Women Fitness Bracelet Tracker Heart Rate Monitor Waterproof Children Sport Smart Band Reloj Mujer - AliExpress
I am not sure if the heart rate monitor fully works properly. It doesn't show up on my list of possible Bluetooth connections, and the only app I was
Mi Pulse Pink/Gray Smart Sports Bra with Heart Rate Monitor Attachment
Heart Rate Monitor Sports Bra
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Gymshark Strappy Back Light Support Sports Bra - Raspberry Pink