Question about Garmin HRM-Run

Hello, you mean the HRM Dual? Unlike the red HRM Run, it has Bluetooth, which you don't need for the connection to the Fenix. The Run has these Advanced Running Dynamics values such as vertical movement or stride length, which you can see on the watch and the app. If you run a lot, the values are still exciting, otherwise I would stay with the Dual - the heart rate sensor is the same.

the HRM-Dual has the advantage that you can remove the sensor and wash the belt without the sensor. if the black one still runs perfectly, you only have to change it if you want to use the Running Dynamics.
the only problem I had with the black one was that the poor quality screws for the sensor lock "broke" when I changed the battery (cross recess slipped out) and I could no longer turn the screws. but maybe they are better in your version...