The "FS" antennas are 100% American made with 100% American materials. To maintain a balance between flexibility and ruggedness, we use a custom blended, glass fiber reinforced shaft. Each is wound with heavy insulated copper wire to prevent the oxidation and shorted windings often found on non-Firestik antennas. The tunable tip mechanism is made from rust-proof brass and has a rubber o-ring to hold the adjuster in place after tuning. Our 3/8"-24 threaded base has a tapered contact point that works especially well with Firestik mounts and accessories. The tapered "lug-nut" effect transfers stress away from the threads and reduces the possibility of vibration induced loosening of the antenna in its mount. Each antenna is covered with a static reducing, water-tight sleeve containing UV and pigment stabilizers. For peek performance we recommend that you use one of our 18-foot Fire-Flex coaxial cables with these antennas.