Antenna Extenders. Constructed of high-quality reinforced fiberglass and finished to match Digital Antennas award-winning antennas, our antenna extenders are used to increase the height of an antenna to improve effective range or to place an antenna above on-board obstructions that may interfere with proper radiation.. All extenders mount standard 1"14 threaded mounts. Use a center brace when the combined length of your antenna and all extensions is more than 8'. All Antenna Extenders Feature:. Heavy duty fiberglass. Stainless steel ferrules. 1"14 threaded top and base. High gloss urethane finish. 528-EW. Dimensions: 4' - 1" O.D.This product may not be returned to the original point of purchase. Please contact the manufacturer directly with any issues or concerns.