The 4008 Series Extension Masts are manufactured of the same Shakespeare fiberglass reinforced composites as our fine antennas. Use them to extend the reach of your marine antenna by increasing its height above the water. - IMPORTANT! If the combined length of your antenna and all extensions is more than 8 feet, you MUST use an upper support bracket. - Heavy duty Chrome plated brass ferrules - upper: male; lower: female Standard 1 - 14 thread male and female fittings. Actual length: 50