Studs Cylinder 99-17 Tc 20-20412Cylinder Stud KitThe complete surface has been ground to remove all the imperfections of standard rough milled material, which also removes notch sensitivity A radius is ground on the last thread to reduce the potential of the stud failing at that point Made of milled and certified 180,000 psi yield strength aircraft quality materials Threads are rolled under hydraulic force, creating the strongest possible thread Made in the U. S. A.