Help! Which Thule bar fit kit on roof rails

Hey all,

I installed some junkyard flush mount roof rails on my bed cap, and I’d like to put crossbars on the cap. There are plenty of cheap Thule bars on marketplace near me, but I’m having a hell of a time figuring out which fit kit I need to get it on flush mount rails. They look nearly identical to the standard Thule rails, I just can’t figure out which one. I’d ideally like to pickup a used set on eBay to keep the cost down. Any advice I’d appreciated! TIA