This is a LBE Unlimited Buffer known as the Recoil Buffer, model ARBUFF.
LBE AR15 Standard Carbine Recoil Buffer is the most widely used buffer in our recoil buffer family. It can be utilized across many different styles of carbine builds featuring different barrel lengths and gas port sizes. LBE Unlimited is a leading producer of US Made gun parts and accessories.
Features:
LBE AR15 Standard Carbine Recoil Buffer
Three Steel weights inside buffer body
MADE IN THE USA