Roof Rack info for 2003 Pathfinder

[FarmNissan]

My 2003 Pathfinder's roof rack has several floating threaded bits in the track channel on both sides.

I had assumed these were used to screw in tie down clips or rings that could then be used to secure cargo between the rails.

Imagine my surprise when no one at the Nissan dealership could provide any info about them.

Does anyone out there have any idea as to either what these are or where to get the tie downs in the event that I am correct as to their purpose? I'm in Toronto, Canada

[SayNoToPistons]

Same thing when we brought our QX4. We have two tie downs on each side and there are also two more threads on each side with no tie downs. If thats what you're talking about?

[FarmNissan]

So, do you actually have tie downs that are able to move within the track between the two crossbars? I seem to have the bits in the track and they slide back and forth, but they are recessed within the track and seem to need a part screwed into them.