BCM-MK2RMS-M1T0 BCM MK2 Recoil Mitigation System - Mod 1 - T0 Complete Kit Features: Lessens felt recoil, without compromising reliability Provides a more consistent carrier velocity, which can aid in accuracy, reliability over conventional carbine buffer system Increased internal counterweight travel reduces bolt bounce Internal spring to reduce noise of counter weight shifting and ensure more consistent weight placement Mil-Spec M16A4 rifle spring with more spring coils than M4 carbine, increases consistency and widens operating envelope Buffer made of 7075T6 aluminum, hard coat anodized for lasting endurance. Comprised of Mil-Spec components BCM US Patent #10415907 This kit contains all the necessary parts to mount to your Mil-Spec dimension stock assembly to your Mil-Spec lower receiver. MK2 Mod 1 - T0 Buffer (weight = approximately 3.8oz) Mil-Spec M16A4 rifle action spring Mk2 Receiver Extension (approximately 3/4" longer than carbine), 7076T6, 8 position, Mil-Spec diameter Lock Nut (Castle) M4 Receiver QD End Plate (include mount for QD swivel) (PLEASE NOTE: because of the MK2's longer length some Mil-Spec stocks may not completely collapse closed all the way up to the M4 Lock nut.)