The M475HD antenna is a 7mm thick heavy duty fiberglass collinear covered with polyolefin for heavy duty use and weatherproof protection. The M475HD works best when mounted onto a bracket that is as close to the surface of the ground plane as possible such as the BMB mount. Do NOT use a spring base or Z bracket mounts with this antenna, use the BMB Mount for the best performance and SWR! Recommended Accessories - UL12C with BMB or MAG12C works best on the RF470 range or raised feeds.