[Universal Diameter and Available Size] Still bothered by the fact that some bike training wheels can only fit one or two sizes of bicycles? Our training wheels with bracket attached feature 5 various holes to fit bicycles with wheel sizes: 12, 14, 16, 18, and 20 inches. The round design and attractive appearance complement each other, offering a fun look that children enjoy. (Note: Not compatible with variable-speed bicycles) [Thickened Wheel with Quality PU Material] Designed for quiet, durable performance, these training wheels are made from high-quality PU material that provides excellent wear resistance and shock absorption. The wheel thickness measures 2.5 cm, which is 0.5 cm thicker than standard models, helping to reduce bumps and deliver a smoother, more comfortable ride with less effort. [Double Bearing and Larger Washer] Featuring optimized double high-carbon steel bearings, these training wheels operate quietly and smoothly while offering extended service life. The enlarged washer fully covers the bearing, reducing the risk of loosening or detachment during use. This added security helps prevent unexpected falls, promoting safer riding for your child. [Thicker Bracket, Stronger and More Durable] Unlike standard brackets that may bend or break, this model includes a 3 mm thick bracket—20% thicker than typical versions—for enhanced strength and support. The reinforced design resists deformation, ensuring long-term durability and giving children greater confidence as they learn to ride. [Easy Installation] Comes with a wrench for simple setup. The locking brace helps secure the bracket firmly to the bicycle frame. Installation is straightforward and user-friendly. For optimal performance, adjust the training wheels so they are approximately 5 mm above the ground when the bike is upright. This allows room for balance development while providing stability during learning. Color: Pink Material: Plastic Package Contents: 2 x Wheels 1 x Wrench 2 x Screws and Nuts 2 x Cushions Only the above package content is included; other items are not part of this sale. Note: Lighting and display differences may cause slight color variations between the image and the actual product. Measurement error allowance: +/- 1–3 cm.