Description Nylon Square Tube Top Insert – Black – 1″ Top Fittings connect to tubing as a Top Cap or Top Insert for 3/4 or 7/8 round tubing or 1 square tubing. Top Fittings create an attachment point and function as a pivot point as part of a Bimini top system. Pin size 1/4. Constructed of UV stabilized injection molded nylon. Available in black or white. Stainless tube wall thickness 0.049. WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.