This upgrade will REPLACE the Mountain Bike Wheels that come standard with a GRIT Freedom Chair 3.0. The price reflects the difference between the two options. Only order this item if also ordering a GRIT Freedom Chair 3.0 at the same time. If you already own a GRIT Freedom Chair and are looking to order an additional set of Sand/Snow Wheels, select this product instead. Reach out to GRIT with any questions.