Amazon.com : COOSPO Bluetooth Heart Rate Monitor Chest Strap H808S, ANT+ BLE HR Monitor Chest, HRM IP67 Waterproof, Use for Running Cycling Gym and Other Sports : Sports & Outdoors
Heart rate monitors: Chest straps v wrist - Wareable
Chest Strap or Wrist-Based Heart Rate Monitors: Which Is Better? – Triathlete