This 16" barrel is part of your DG (duty grade) series of barrels.
Specs:
Length: 16"
Chamber: 5.56x45mm (5.56 NATO)
Feed Ramps: M4
Gas System Length: Carbine-Length
Twist Rate: 1:7
Muzzle Thread: 1/2x28 RH
Coating/Treatment: Chrome Lined, Phosphate Coated
Gas Block Journal Size: 0.750"