This 21’ one section, 350 watt 50 Ohms VHF Marine Band 10dB gain commercial antenna was designed for heavy duty sea going applications, such as work boats, tugs, tidal well service boats, etc. It is also an excellent choice for use as a VHF land base station. Designed to get transmissions through by radiating the signal on the horizon, providing gain in all directions. Features phased 1/2-wave elements in a collinear array with a broadband matching section, a coaxial choking sleeve. The 2.75″ diameter x 26″ long 6061-T-6 aluminum sleeve can be strapped directly to a mast or wall with Shakespeare 483 clamp or 484 wall mounting brackets (not included). Constructed of brass and copper internal elements for superb durability. S0-239 connection at the antenna base. In white. Truck shippable only.