CB radio antenna springs will provide flexibility and protection against damage.
Protect Your Antenna With A Stainless Steel Spring. Allows your antenna to flex when encountering trees and other low hanging obstructions. Heavy-duty means it only moves when it needs to.
CB Antenna Spring Firestik - SS3M - Stainless Steel Spring
CB Antenna Spring KA52SS 4in Stainless Steel Pot Belly Heavy Duty Spring