Won't be able to measure them until at least the weekend.
To get a rough idea, I believe you are looking at the minimum, which is around 5'. If you look at the shaft with the holes in it that protrudes down the center, that's how much taller they get in addition to the threaded, adjustable portion. They can almost double in height.
There used to be a set of four, but SilverXJ told me the other two disappeared to New Zealand while I was overseas. I don't really know what that meant.