I'm guessing that you insert a hex key into the hole and turn it.
Cervelo S2 | Zipp | SRAM | Rotor
Yes with a hex key, you can turn the bottom to make the shock firmer. I have to say that if you are someone weighing more than 200+ those post don't do much but stay down. We tighten the one my cousin had on his bike and it just did not work with his weight.
Giant Anthem X 29er - Jamis Dakar Sport 26er