Hy-Gain AV-18HT Instruction Manual page 26

The tower plates inside the Hy-tower have
been improved. The new plates are made from
stainless steel, Install the lower plate as shown
in the diagram, One X has been left out of the
top section to allow for easy installment of the
lower ( larger) triangle. Install two spacers
between the triangle tab and the tower leg,
The upper plate should be installed with the
triangle tabs on the outside of the tower
legs, Use the 1/4-20x 1/2 bolts for the upper
(small) triangle, Make sure that both of the
triangles are oriented the same way,