This 140 mm rear brake disc for the Fit Right FRP DB001 50cc dirt bike is a perfect replacement for the factory-installed brake disc on your FRP DB001. The brake disc has a 140 mm (5-1/2") outer diameter. It sports 3 mounting holes that are on a 33.4 mm (1-5/16") bolt hole circle. Each hole is 6.2 mm (1/4") in diameter.