Every antenna should have a spring. Springs protect the antenna, mount and vehicle. These springs are made from long lasting, top grade electro-polished stainless steel.
The upper and lower inserts are made of chrome-plated machine brass and have standard 3/8"-24 threads to fit all Firestik antennas, mounts and accessories. The medium duty model works especially well with our 2ft "KW" & "FS" series antennas as well as the 3ft "FL" or "RP" antennas. Each spring is about 3.0" (76mm) tall with a diameter of 0.800" (20mm).