Why medical grade when you can easily count it with a finger and another timer? Want MORE accuracy? Then count out the full minute rather than average from 15 seconds. It's not that hard to do, and you certainly don't need "medical grade ECG" to do this simple HR check. If you do think you need the medical grade ECG, perhaps there's something wrong with your brain? Then you need to go and get a "medical grade EEG" and do let us know how that goes?