◾️The Wahoo KICKR CORE is a high-performance indoor training base equipped with a Shimano cassette. I purchased it at a cycle shop and had them install a sprocket on the KICKR CORE unit. I had them set it up so I could quickly attach my cross bike, which I also use outdoors, and use Zwift indoors. It will be delivered with the sprocket already installed. ◾️Sprocket Model Number: Shimano CS-HG41-8 ◾️Used, no noticeable scratches or stains ◾️Operation confirmed - Brand: Wahoo - Model Name: KICKR CORE - Accessories: Power adapter, instruction manual, mounting parts - Gear Type: Shimano cassette - Color: Black