The yoke clamp base will fit rails in diameter from 0.625 inch to a maximum of 1.25 inch. The 1 inch rubber ball is at a right angle to the plane of the mount; when connected to a rail, the ball sits parallel to the rail.
Material: Powder Coated Marine Grade Aluminum
Ball Size: 1″ Rubber Ball “B” Size
Note: Product packaged in poly bag. The rail does not need to be perfectly round to mount this base.