Using Mi Band with Nike Run Club (and any other fitness app which supports iOS HealthKit) : r/miband
Heart Rate Meter Bluetooth Pulse Sensor Cardio Sport Chest Strap Belt Heart Rate Monitor Polar Style Heart Rate Meter For Sport - Outdoor Fitness Equipment - AliExpress
Nike Running with Heart Rate and GPS - Apple Community
Herzfrequenzmesser sPulse Pulsmesser mit Armband per Bluetooth & Sensor LED | Smart HRM Pulsuhr ohne Brustgurt Fitness Schrittzähler Sense Run : Amazon.de: Sport & Freizeit