Acme

Features and Specifications:
Mil-spec Diameter Receiver Extension Tube for AR-15 Rifles
Extension Tube CNC Machined from 6061-T6 Aircraft Grade Aluminum with Precisely Rolled Threads for Durable Thread Engagement with Lower Receiver
Finished in Matte Black Type III Class II Hard Coat Anodize
Material: Aluminum
Height: 1.45"
Length: 7.25"
Weight: 9.3 oz
Color: Black

Includes:
Mil-spec 6 Position Extension Tube 
Carbine Buffer 
Buffer Spring 
Receiver End Plate
Castle Nut