Amazon.com: BoxWave Cable Compatible with Polar M400 (Cable by BoxWave) - Micro USB DuraCable, Braided Micro USB Charging Cable for Polar M400 - Space Grey : Electronics
USB Kable Battery Charging Charger Cable Cord Lead for Polar M400 A370 A360 RC3 | eBay
Maintenance of your M400 | Polar USA
Charger Cradle Charging Line for polar M430 M400 Dock USB Charging Cable Dock Chargers| | - AliExpress
Polar M400 User Manual
USB Charging Cable M400 Charger Compatible with Polar M400, M450, A360, A370, V700 Sports Watch USB Charger Cord - Newegg.com