Help: Plastic Axel Shaft 'flanges' (Slinger?)

Since I needed to pull out my axels to replace ball joints, I picked up a new set of the long since departed plastic rings that attach to the axel shaft and prevent junk from entering the axel tube (a slinger?). Which way do the rings face - with the plastic flange facing in or out? - Does it matter?

89 XJ, Dana 30.

Thanks for any advice.

the stiffening ribs face outward, the flat surface faces inward toward the axle tube iirc.

Thanks Kastein!