The UTG Mil-Spec Receiver Extension Tube Kit is made from 6061-T6 aluminum with rolled threads and a matte black hard coat anodized finish. Included is a 6 position extension tube, carbine buffer, buffer spring, receiver end plate, and a castle nut. Made in the USA.
Specifications:

Type	Buffer Tube Package
Model	AR-15
Dimensions
Size	Mil-Spec
Material	6061-T6 Aluminum
Action
Trigger
Safety
Thread Pattern
Finish	Black Hardcoat Anodized
Bolt Type
Hand
Hammer Type
Max Capacity