Sea Dog Rail Mount BracketInjection Molded Nylon/Stainless. Sold as pair.All Sea-Dog Rail Mount Brackets are designed for easy attachment to 7/8" - 1" tubing. The injection molded nylon mounting parts and rubber liners allow for positive attachment without scratching or marring the tubing.Dimensions:327101-1 (round) A: 3/4"; B: 2"; 327102-1 (square) A: 1-3/4"; B: 1-3/4";