12″ STAINLESS STEEL ANTENNA EXTENSION – 1″X14 STANDARD THREAD. Glomex antennas’ extensions are used for vertical elevation of the antenna in order to clear the reception/transmission field. They can be made of stainless steel or UV resistant fiberglass, with standard 1″x14 thread, and they are the ideal complement to all Glomex antennas (VHF, AIS, etc.).