Keep your child safe and confident - These handy 3mm thick bike training wheels add the reinforcement clip to build the sturdy triangle design helps learners develop a sense of balance usable on the bike, prevent children from worrying about the fight because of the bicycle. High Quality Flash Wheels - Non-slip, wear-resistant, stability, the support arms of the training wheels are 3.0mm thick, it will be more safety and stability for beginners. The black wheels match any color bike perfectly. Universal and Adjustable - The stand wheels fit 12/14/16/18/20 inch single speed bikes with a rear-facing track fork end, but will not fit those with semi-horizontal dropouts or vertical. Cannot be installed on bikes with derailleurs or drivetrain. Easy to install - Included 2 x vertical support arms, 2 x wheels, 4 x nuts (2 spare nuts), 1x screwdriver, 1x spanner, 1x bike bell. Go and enjoy your first outdoor cycling exercise with your kids . Installation - 1.Connect the drive wheel and support bar together. First put the screw, drive wheels, gasket, support bar and nut in order, then fix them with a wrench. 2. Attach the stopper block, remove the rear axle nut from the bicycle wheel, attach the pointed horn of the stopper block to the bicycle frame. 3 According to the size of the bicycle wheel, choose the appropriate location of the hole on the support bar.