1. [Universal Diameter and Compatible Sizes] Are you concerned that some bicycle training wheels may only fit one or two sizes of bicycles? The training wheels with a bracket having 5 different mounting holes can meet your needs to install them on 12 - inch, 14 - inch, 16 - inch, 18 - inch, and 20 - inch bicycles. The round and lovely appearance is well - matched, like a blue lollipop, bringing colors to your child. (Note: Not suitable for variable - speed bicycles.) 2. [PU Material Thickened Wheels] We've been looking for bicycle training wheels that are quiet, wear - resistant, and shock - absorbing. The training wheels made of PU material meet these requirements. The 2.5 - centimeter thickened wheels (0.5 centimeters thicker than some ordinary training wheels) can reduce bumps, make cycling easier and more labor - saving, and offer a certain level of comfort. 3. [Double - layer and Larger Washers] After optimization, the double - layer high - carbon steel of this training wheel has been tested to be relatively quiet and durable during use, which can extend the service life of the wheels. Additionally, the washers have been specifically enlarged to completely cover the corresponding parts. So, even after your child has been riding for some time, there's less worry about the training wheels suddenly falling off and causing the child to fall. The child can ride safely. 4. [Thicker Bracket, Stronger Support] Have you ever encountered the situation where the bracket of the bicycle training wheel deforms or breaks? Considering this, we've designed a training wheel with a bracket thickness of 3 millimeters, which is about 20% thicker than some ordinary brackets and has relatively stronger support ability. Therefore, it's less likely to deform or break. Your child will be safer when enjoying the fun of learning to ride a bicycle. 5. [Easy Installation] Equipped with a wrench, you can complete the installation. The locking buckle is useful for fixing the bracket and the bicycle. It's quite simple. At the same time, we recommend that when the bicycle is parked, the training wheels are about 5 millimeters from the ground, which helps the child master the sense of balance while riding. Color: Black Material: Plastic Package Contents: 2 wheels 1 wrench 2 sets of screws and nuts 2 cushions Only the above package contents are included, and other products are not included. Note: Light and different monitors may cause a slight difference between the color of the product in the picture and the actual item. The measurement error is allowed to be ±1 - 3 centimeters.