S&W M&P15 PS Description (https://www.midwayusa.com/product/1016484156?pid=452894)
These are gas piston complete uppers chambered in 5.56. I have two for sale
Retails for $800+ IF you can find them.
1 new in box $450 obo
1 new but lost box $400 obo
Never installed. Just don't have need for them any more.
Photos (https://imgur.com/gallery/MnIBpk3)