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 range:
0.625" - 1.25" (1,587 - 3,175 cm)
Ball size:
B Size (1" / 2,54 cm)
Materials:
Marine-grade aluminum