Rob ter Horst uses a Polar H10 chest strap as a refernce device for his accuracy studies. Cardiologists from the Cleveland Clinic in Ohio tested the accuracy of heart rate monitors: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6732081/ They compared the accuracy of the HRM they tested to a Quinton Q-tel RMS telemetry system: In this paper it says: «The Mason-Likar …