[Universal Diameter and Available Size] Tired of bike training wheels that only fit one or two bicycle sizes? Our training wheels feature a bracket with 5 mounting holes, compatible with bicycles sized 12, 14, 16, 18, and 20 inches. The round design and attractive blue finish resemble a lollipop, adding fun and color to your child’s riding experience. (Note: Not suitable for variable-speed bicycles) [Thickened Wheel with Quality PU Material] Designed for durability and comfort, these training wheels are made of high-quality PU material, offering quiet operation, wear resistance, and shock absorption. With a 2.5 cm thickness—0.5 cm thicker than standard wheels—they help reduce bumps for a smoother, more comfortable ride. [Double Bearing and Larger Washer] Equipped with dual high-carbon steel bearings, these wheels deliver smooth, quiet performance and extended lifespan. The enlarged washer fully covers the bearing, preventing loosening or detachment during use, helping to avoid sudden drops and ensuring a safer riding experience. [Thicker Bracket, Stronger and More Durable] The training wheel bracket is 3 mm thick—20% thicker than standard brackets—providing enhanced strength and support. This design resists deformation and breakage, offering reliable stability as your child learns to ride with confidence. [Easy Installation] Comes with a wrench for simple setup. The locking brace helps secure the bracket firmly to the bike frame. For optimal balance training, adjust the wheel so it is approximately 5 mm above the ground when the bike is upright. Color: Blue Material: Plastic Package Contents: 2 x Wheels 1 x Wrench 2 x Screws and Nuts 2 x Cushions Only the above items are included; other products are not included. Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement allows for an error of +/- 1-3 cm.