Yes, they are meant to work with extensions of 1" O.D. aluminum tubing available in 6', 8', and 10' lengths, in gold anodized or white. They are awesome, nearly lifetime antennas. It's what the commercial fishermen use in the NW. I have had a couple for fifteen years.
Thanks Steve. Can't beat that price, just ordered one and got the base and extension from Fisheries Supply. Sounds like I won't be worrying about buying a new one for a long time.