U-posts are made from Medium duty steel13 or 14 gauge steel, with a U-shaped cross-section, classified two types with spade or without spade, easy to install in the earth while staying sturdy under pressure.
They’re fitted with studs along the spine to help keep the chain link taut. U-posts are available in durable rust-resistant green PVC coating, excellent for supporting lighter-weight fencing materials.
If you worry about goats or ponies lean on T-posts, then bend or push outward you can try U post, cost usually half of the price of T posts.