Axle dimensions are given in millimeters unless stated otherwise. There are 25.4 millimeters per inch. Due to the wide variety of axles that come on gas and electric scooters, pocket bikes, mini choppers and all other vehicles it is difficult to determine a specific axle for any vehicle. Please measure the length and width of your existing axle to compare to what we have on this online store. Measurements can generally be within 5mm either longer or shorter and will still work.