The yoke clamp base will fit rails in diameter from 0.625" to a maximum of 1.25". The 1" 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.

Clamp Base Dimensions:
Accommodates rails from 0.625" to 1.25" in diameter

Material:
High Strength Composite and Powder Coated Marine Grade Aluminum

Ball Size:
1" Rubber "B" Ball Size