Radio Research, Inc.

Firestik plated CB antenna spring, heavy duty, designed to add flexibility to your antenna, protecting it, the mount, and your vehicle from damage by low-hanging branches or accidental bumps. Ideal for 3-4 foot antennas. P/n SS-3H. Made in USA.
The best way to protect your antenna, mount and vehicle from damaged caused by accidental contact is to use a spring. This springs is made from spring steel and is chrome plated. The upper and lower inserts are made of chrome-plated machine brass and have standard 3/8"-24 threads to fit all Firestik, FireFly and RoadPal antennas, mounts and accessories. The spring inserts, on both ends, have female threads. A stainless steel 3/8"-24 stud is included for use on standard antenna studs and fittings. The heavy duty model may be used with antennas up to 60". Physically, this spring is about 3.0" (76mm) tall with a diameter of 0.800" (20mm).