These are the only pics to go on.
There were no PB2110 stamp or connectors that could be observed.
The clothes washer supply valve handle (looks original) says “Qest”.
Some Poly was primarily under the brand name Qest so it logically seems to be.
House built 1980.
Thank you! 
Yes, poly
After the $45k + in damage to my son’s house after one of these plastic piece of **** valves broke in the middle of the night, I don’t care if they are poly or not, I recommend replacement.
I wanted to hear it from someone else, THANKS Joshua! 
Looks like PB to me.
Yes…PB
Yep…Looks like PB.
It’s unanimous… polybutylene piping: Source Plumbing express…
Polybutylene Plumbing - What is Polybutylene?