All KOAH Shafts a constructed from the highest grade centerless ground 17-4 stainless steel which is machined and heat treated in house. Since our steel is centerless ground that means the selected size of the raw shaft material is actually ground down from a larger diameter. This means that the final diameter of the shaft is extremely accurate and larger diameter imperfections and steel stress points have been removed. All KOAH Shafts a constructed from the highest grade centerless ground 17-4 stainless steel which is machined and heat treated in house. Since our steel is centerless ground that means the selected size of the raw shaft material is actually ground down from a larger diameter.