DescriptionMaterial : SteelGear Teeth : 10-51TFreewheel Speed : 12Brand Name : SHIMANOOrigin : JP(Origin)Components : FreewheelAll specifications on this page are "OEM version" products, which are original Shimano products, and the "OEM version" products are supplied to bicycle manufacturers for bicycle assembly, and this product will become part of the bicycle in the bicycle manufacturer's production workshop. For manufacturers, they don't need beautiful packaging to fit more product in the same size package. So they are more cost-effective than the "consumer version". FOR EXAMPLE, YOU BUY A BICYCLE AT TREK BIKE SHOP. All the parts on this bike come from the "OEM shipping channel," and when your tire is damaged and you need to buy a new one, you'll look in the store for a consumer version with a nice package.