Polar Verity Sense - Bracelet with Optical Pulse Sensor - ANT+ Dual Bluetooth - Pulse Sensor for Sports with Just One Button - Compatible with Peloton, Endomondo, Zwift and Others Amazon Exclusive :
Review: Polar H9 heart rate sensor | road.cc
Polar Verity Sense optical heart rate sensor - Wattbike
Polar H10 Heart Rate Monitor: Very Long Term In-Depth Review | DC Rainmaker