Just to be fair…
I wondered the same thing recently when I received my new CLYW. I have always loved the old yellow YYN Highlights. I have never found anything that is quite the same. I have tried the YYE standard yellow, onedrop standard, YYE expert string, the green Duncan strings, Kitty String, and a bunch of others. I know they say they are the same. It might all be in my head (Prob) but none of them felt quite like the old YYN highlights.
But the green string that came with my CLYW felt like the old YYN Highlights.
So I wondered what the string was myself.
It’s finny when you google search a question you have and come across a thread full of no answers to the question…wish that google would omit these kind of threads from search results…