Lowe's sells these pipes in 10' and 100' lengths. I need 14' to attach to a
downspout.

The Internet advertises expandable pipes, e.g., 3' can expand to 12' and a
6' product can expand to 25'. How do these work? The extensions are
obviously inside the collapsed pipe, but I can't see how they would maintain
the same diameter/circumference. They must be narrower. Pls. educate me.
Thanks. - - Jack