Threadless Bicycle Stem Road Mountain Hybrid Bike W/Asst Of Simons Spacers (16) The product is a black threadless bicycle stem made of aluminum, designed for road bikes with a handlebar clamp diameter of 31.8mm. It comes with a headset, gaskets, and includes 11 assorted spacers for customization. The stem is 100mm in length and is manufactured in China. This high-quality stem is a perfect addition for cyclists looking to enhance their road, mountain, or hybrid bike's performance and style.