This steel tubing is ideal for making your own tie rod, trailing arms or other suspension components. The 5/8" tap tube features .812 O.D. with .562 I.D. that is ready to be tapped to 5/8-18. The 3/4" tap tube features .937 O.D. with a .687 I.D. that is ready to be tapped to 3/4-16.