Sounds like the ones I installed last year. If it is, you remove
the
piece of wood that is raised and lowered, and under there are some
screws, or at least that's where you attach it using plastic or lead
shields, or whatever is needed for what you're going into. That way
the
screws are hidden.

Get 3-fin rubber sweep, and you'll never have a draft or moisture.
The
wood acts as a thermal break.



The ones I was looking at in the store were just flat underneath. Are
you
saying, if I remove the wood strip I will see screws or something
underneath
it that will go through the base and into the slab? (I have a slab)
What
is a 'shield'?

Yes, remove the adjustable wood strip. I don't remember if there are
holes already, or if you have to drill them. In either case, this is
where you attach it to the subfloor. The other poster should have
described what a shield is. Basically the plastic sleeves that you use
on drywall. If you sub-floor is wood, just use a wood screw.