Those are pretty nifty, they are quick releases that only release when the bike it upside down. I have a set on my wheels.

They aren't the most secure thing, but they will do plenty to stop the casual thief, and unlike most other security skewers, they can't be opened with needle nose pliers and a few flat screwdrivers.

Opening a saddle QR while the bike it upside down might be awkward though.