The 144-175 MHz COL range is a series of "cut to frequency" 3dBd gain vertical collinears. The range includes antennas suitable for simplex, duplex and rugged applications. All of the antennas include internal DC grounding for lightning protection and the reduction of static noise. Drainage vents at the base allow the antennas to 'breathe' and thus prevent condensation build up. The alodine finish of the aluminium mounting tube provides a conductive surface which ensures effective earthing when mounted.