MAVIC Computer Magnet for TraComp Spokes, Silver. Although there is only one set of parts to fix the magnet to the spoke, I was able to use them by attaching one to the top and one to the bottom of the magnet on each side, and it didn't move at all. I used it on round spokes for about 500km, but I need to replace the wheels, so I'm selling it. Thank you for your consideration.