For use in 10 and under tennis, this SET of posts are external wind 13 gauge galvanized steel with triple coat corrosion protection, the winding mechanism is all-aluminum with aluminum post caps. They are available in 2 7/8" only and in green only. Posts are built for permanent installation or semi-permanent with purchase of ground sleeves. Use with Quickpost PVC ground sleeves 390005 Or direct bury.