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″