KEEP YOUR CHILD SAFE AND CONFIDENT - These 3mm thicker training bike training wheels feature extra reinforcement clamps to create a robust triangular design that helps learners develop a useful sense of balance on the bike and prevents children from worrying about falling off their bikes.<br> High-Quality Flashing Wheels - Non-slip, wear-resistant, and stable. The training wheel support arms are 3.0mm thick, making them safer and more stable for beginners. The black wheels are perfect for any colored bike.<br> UNIVERSAL AND ADJUSTABLE - Support wheels fit 12/14/16/18/20 inch single-speed bikes with horizontal rear dropouts, but do not fit semi-horizontal or vertical dropouts. Cannot be mounted on bikes with gears or derailleurs.<br> EASY TO INSTALL - Includes 2 vertical support arms, 2 wheels, 4 nuts (2 spare nuts), 1 screwdriver, 1 wrench, 1 bicycle bell. Go and enjoy your first outdoor bike ride with your children.<br> Installation -<br> 1. Fasten the training wheel and support rod together. First, install the screws, training wheels, spacers, support rods, and nuts in sequence, then secure with a wrench.<br> 2. To secure the block, remove the rear axle nut from the bicycle wheel and attach the pointed corners of the block to the frame.<br> 3. According to the size of the bicycle wheel, select the appropriate hole position on the support rod. The training wheel should be about 0.5-1 cm (1/5 to 3/5 inch) above the ground. Tighten the axle nut with a wrench.<br> Material: Metal<br> Color: Red, Purple, Green, Blue, Black, Pink<br> Size: 12-20 gimbal mount<br> Package List: Bicycle training wheels*1