Keep your Child Safety and Confidence - This 3mm thickening practical bicycle training wheels add the reinforcing clip to build the sturdy triangle design assists learners to developed a usable sense of balance on the bicycle, avoid children worrying about wrestling because of cycling. High Quality Flash Wheels - Anti-slip, Wear resistant, Stability, training wheels bracket arms are 3.0mm thickness, these will be more security and stability for beginner. Black wheels fit perfectly on any color bike. Universal and Adjustable - The support wheels fits 12/ 14/ 16/ 18/ 20 single-speed bike inches with horizontal rearward-facing track fork end, but not suitable for those with semi-horizontal or vertical dropouts. Cannot Be Installed On Bikes with Derailleurs or transmission. Package included: 2pcs bicycle flash wheels