Steel, cres per astm a581 or astm a582; 0.335 in. Min. And 0.345 in. Max. O/a lg; 0.015 in. Min. And 0.025 in. Max. Distance from end to first step; 0.479 in. Min. And 0.489 in. Max. Od; 0.1874 in. Min. And 0.1876 in. Max id; 0.500-16un2a, 0.320 in. Thd lg