This a a Palmetto State Armory 16" Black Nitride A2 1:7 Twist Carbine Upper Assembly. Built by PSA and made in the USA!!

Barrel Length 16"
5.56 Nato Chamber
1 in 7" twist
Carbine-length Gas
Black Nitride Finish
.750" Gas Block Diameter
M4 Feedramps
Forged Upper
**Upper may or may not have T-marks
Does not include BCG or Charging Handle

Check out this product on my website! http://www.battlecreekarmory.com/product-p/psaua5561.htm