This is a new-in-box Garmin Speed/Cadence Bike Sensor (GSC 10), a discontinued wireless ANT+ accessory that tracks your pedaling strokes and wheel speed. It mounts onto the rear chainstay of your bicycle and uses two magnets (one on the crank arm for cadence, one on a spoke for speed) to register data. Designed to work with older ANT+ compatible Garmin Edge bike computers (such as the 305, 500, 705) and various Forerunner and Oregon fitness devices. The plastic outer packaging is showing signs of wear but has not been opened? Dispatched Royal Mail tracked 24 within three days. Seller reference H3
