Razor Mx350 Mx400 Kids Youth Training Wheels -TRAINING WHEELS ONLY/BIKE NOT INCLUDED: Fits all years Razor MX350 - 400 Electric Bikes -Mounting: Lock collars prevent from sloppy fitting wheels, that are unstable. This is the best design in the industry. -Engineering: Safe, sturdy design. If we wouldnt put these wheels on our childrens bikes, we wouldnt sell them to you! Our design is tried n true! SAFETY IS OUR MAIN GOAL. -Wheels: Tread style  Knobby All-Terrain / Tire Type  Pneumatic 10 tire / Rated - 300lbs per wheel / Ball bearing wheel hub assembly -Electro Powder Coat: Paint that is baked on at 400 degrees, and tough as nails!