This set of stabilizers assist young learners until they have developed a usable sense of balance on the bicycle. Improve your child's safety and confidence without holding the back of the saddle .Wheels diameter:4.33 inch. Universal training wheels fits for 12/ 14/ 16/ 18/ 20 inch children's bicycles. Tips: For Single Speed Bikes Only (Cannot Be Installed On Bikes with Derailleurs) and Supports Riders up to 100 Pounds .These bicycle training wheels are made of high quality plastic and rubber which it is anti-slip, wear resistant, providing stability and help children to ride a bike without fear. Light weight and noiseless.Easy to install, all mounting hardware and installation instructions is included, you will have more choices to adjust the height.When young children start to ride a bike,the first thing they need to gain is a sense of balance. Training wheels or stabilizers are an additional wheel or wheels mounted parallel to the rear wheel of a bicycle that assist learners until they have developed a usable sense of balance on the bicycle.The kids bike stabilisers is very sturdy and simple to install suit for 12 14 16 18 20 Inch Training Wheels.Size: Wheel: 4.33 inch x 4.33 inch x 0.98 inch /11cm x 11cm x 2.5cm Bracket Arms: 10 inch x 1.1 inch / 25.4 cm x 2.8 cmFit: 12/ 14/ 16/ 18/ 20 inch BicyclesINSTALLATION NOTES:1.Insert through the wheel, washer and training wheel arm.2.Attach and tighten washer and nut, you will require two wrenches to tighten this propeily.3.Remove rear axle nut from the bicycle wheel axle.4.Insert axle though locking brace and fix the raised point to the bicycle frame ends .5.Determine desired height of training wheels when attached the training wheels should have about 0.5-1cm (1/5 to 3/5in) space from the ground.6.Tighten axle nut with adjustable wrench .7.Repeat for another suide.Material:Steel+plastic+rubbercolour:blackPackage Contents:2 x auxiliary pulleys1 set x installation componentsOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.