DoubleStar is a high quality manufacturer of AR-15 parts and accessories. This particular part is a receiver extension/buffer tub for an AR-15 pistol build. It includes the carbine length spring and buffer, and features a 1.25″ ambidextrous sling mount.

Specifications
7075-T6 Aluminum
Overall Length: 7.25:
1.25″ Ambidextrous sling mount
Billet Machined Gusset
Foam OverTube (cut to length)
Carbine buffer and spring included

Fits: AR15 Lower Receivers
Kit Includes: Buffer tube; Carbine buffer; Spring; Foam Sleeve; Stock plate with swivel