RobA,
I purchased stainless steel square cross-section fence post that was cut in lengths of 10, 9, 8 and 7 feet for no charge by the fence company.
We used a post hole digger to bury the posts at least four feet deep, then used quickcrete to stabilize the outside of the posts and poured some inside as well.
It feels like it's anchored to the earth's core.
