This thing has no spring or post where the addy connects, it's just a hollow tube. How is anybody using this?
What are you talking about? If you're looking at the 'upgrade tube', of course it's just a hollow tube, it's there to 'upgrade' an SP2 unit to a THERMO, by replacing SP2's body/tube.
You need to look at the full or base kit, which includes the end button and the atomizer connection.