Cadence magnet, Rare earth attaches to your crank for a sleek look never moves. | eBay
Sigma Cadence Magnet | SPOKE
Wahoo Fitness RPM Cadence Sensor (BT/ANT+) - Wheel World Bike Shops - Road Bikes, Mountain Bikes, Bicycle Parts and Accessories. Parts & Bike Closeouts!
SpeedZone Cadence Magnet | Specialized.com
A Quick & Cheap Garmin Cadence Magnet Replacement - SLO Cyclist | An Online Road Bicycling Magazine
Bontrager 26mm Cadence Band Magnet - Trek Bikes
Giant RideSense Speed and Cadence Magnet Kit - Wheel World Bike Shops - Road Bikes, Mountain Bikes, Bicycle Parts and Accessories. Parts & Bike Closeouts!
Exercise Cycling 2-in-1 Cadence / RPM + Speed Sensor for Indoor or Out
Bontrager 4mm Cadence Band Magnet - Trek Bikes
K-Edge Chain Catcher Cadence Magnet | SRM Shop USA