AR-15 Lower Receiver Block 223 & 556/.308

Also compatible with .308 platforms, providing secure mounting and support for larger AR-10 pattern lower receivers. The expanded platform support allows builders and armorers to service both standard .223/5.56 and .308 receivers using a single bench setup. Locks firmly into a standard bench vise to prevent movement, slippage, and surface marring while installing lower parts, buffer tubes, and trigger assemblies.