Not sure. I haven’t seen any new hybrids on any of the hatchery websites I’ve looked at, so it could just be that they haven’t written a description yet.
My theory is that they’re a cross of the same two breeds as black sex links, except reversed. Instead of barred rock hen x RIR rooster, it would be barred rock rooster x RIR hen. Like red sex links versus amberlinks (amberlinks have the same breeds as RSLs in them, except the parents are...