Our Weldable Low Profile Post Caps are made of mild steel. They come in a variety sizes from 1-5/8″od to 6-1/2″od and have a thickness of .105″, approximately 12GA. They are made to match outside diameter pipe sizes from 1-5/8″ to 6-1/2″. Our pipe caps are used not just as farm and ranch hardware. They are used in a variety of art as well. Bugs, turtles and frogs are a few of the pieces made with our caps.