Upgrade your MVB MPK to a SBR (after receiving your stamp) or simply upgrade your 2 position or multi-position stock (purchased prior to December 2016) to the ARC-X stock model, which is dropped tested to 6 ft. and has an improved locking mechanism.  You can also upgrade to an ARC-X skeletonized butt pad and base block.

Kits includes complete stock assembly excluding buffer tubes, buffer, and springs.  The stock assembly consists of base block, rails, buttpad, and locking mechanism.