priced per ring
135 Bcd
brand new rings, removed from campagnolo 11 speed ATHENA cranks
these rings are matched to go with each other - i'm pretty sure it really affects only the big one - you should use one that's matched to the small ring size, i believe the small ring doesn't have any special differences - these say 53/39 on the large ring so are optimized to shift up and down from a 39t inner ring. a mix and match will still work, especially on friction but ideally the smaller ring should match what's said on the larger ring.
As for the "XPSS" i think that just refers to some small improvements in the lifting/dropping technology - pins, ramps, shaped teeth etc.