[Universal Diameter and Available Size] Tired of bike training wheels that only fit one or two bicycle sizes? Our training wheels come with a bracket featuring 5 different mounting holes, making them compatible with bicycles sized 12, 14, 16, 18, and 20 inches. The round design and attractive blue finish create a fun, lollipop-like appearance that kids love. (Note: Not suitable for variable-speed bicycles) [Thickened Wheel with Quality PU Material] Designed for durability and comfort, these training wheels are made from high-quality PU material, offering excellent wear resistance and quiet operation. The wheel thickness measures 2.5 cm—0.5 cm thicker than standard models—helping to absorb shocks, reduce bumps, and provide a smoother, more comfortable ride. [Double Bearing and Larger Washer] Enhanced with dual high-carbon steel bearings, these training wheels deliver smooth, quiet performance and extended lifespan. The upgraded, enlarged washer fully covers the bearing to prevent loosening or detachment during use. This added security helps reduce the risk of sudden falls, promoting safer riding for your child. [Thicker Bracket, Stronger and More Durable] Worried about brackets bending or breaking? Our training wheel bracket is 3 mm thick—20% thicker than standard brackets—providing superior strength and support. This reinforced design resists deformation and damage, giving your child confidence as they learn to ride. [Easy Installation] Comes with a wrench and all necessary hardware for simple, tool-free assembly. The locking brace helps secure the bracket firmly to the bike frame. For optimal performance, adjust the training wheels to sit approximately 5 mm above the ground when the bike is upright. This setting supports balance development during the learning process. Color: Blue Material: Plastic Package Contents: 2 x Wheels, 1 x Wrench, 2 x Screws and Nuts, 2 x Cushions Note: Other items not included. Slight color variation may occur due to lighting and screen settings. Measurement tolerance: +/- 1–3 cm.