Maxim Defense Industries RDB Roller Delay Blowback System CQB Buffer Hardened Tool Steel. By allowing gas pressure to stabilize before extraction it ensures smoother operation while virtually eliminating friction common in standard buffer systems. NOTE: The RDB System is designed specifically for 9mm AR platforms and is not compatible with other calibers. The RDB system is not full auto rated. Specifications for OpticsPlanet Exclusive Maxim Defense Industries RDB Roller Delayed Blowback System: Manufacturer: Maxim Defense Industries Color: Steel Condition: New Features of OpticsPlanet Exclusive Maxim Defense Industries RDB Roller Delayed Blowback System:Reduces felt recoilincreases reliabilityMinimizes friction for enhanced performance Package Contents: Maxim Defense Industries RDB Roller Delayed Blowback System Instruction Manual Maxim Defense Industries MXM-47838: RDB Roller Delay Blowback System CQB Buffer Hardened Tool Steel