fiber glass extension arms for composite or wood cross arms. Can be used with both our Round and Super U Extension Arms. Fits composite or wood cross arms up to 4 1/4� x 6 3/4�. Super U Arm with Large Hanger Loop fits 5 1/4� x 6�. Rubber grippers won�t damage composite cross arms. Cross arm loop is powder coated to prevent damage to composite cross arm. Casting trim on end fitting provides protection on bottom side of composite cross arm. To order arms found on page 307 and page 308 add -F to the catalog number. Retrofit kit available to convert existing extension arms.