I have been using Bevel for a month now and my HRV (both rMSSD and SDNN) seem to be off from Oura and Whoop. I know Oura and Whoop both use rMSSD, like Bevel, so I am curious as to why there is such a discrepancy.
I have attached my Oura, Bevel, Whoop, Athlytic, and Apple Health data for the last week.
Thanks