PolarGlobal on X: "Today we've launched a new heart rate sensor: Polar H9! - Bluetooth, ANT+ and 5 kHz technologies - Battery life of 400 hours - Compatible with Polar Club Discover
POLAR Heart Rate Sensor H1 Watch Compatible Bluetooth Smart Monitor, New Battery | eBay
Changing battery to Polar H7 heart rate sensor - YouTube
Polar heart rate sensors | Change the battery - YouTube