LBE Unlimited is a quality manufacturer of AR-15 parts and accessories. This particular item is an AR-15 pistol buffer tube receiver extension kit. This Complete kit can be used as a replacement unit or as a spare for a new build. This unit comes with all the parts you need to assembly the stock section of the lower receiver. This kit along with it's components are made right here in the USA.

Specifications and Features:
LBE Unlimited PBUFKT-BLK
AR-15 Mil-Spec Stock Assembly Kit
Great as a Replacement or Spare
Made in the USA
Black

Includes:
Receiver Extension (Buffer Tube)
Castlenut
Endplate
Buffer
Carbine Spring

Fits:
Compatible with Mil-Spec AR-15 Lower Receivers and similar pattern units