This Receiver Extension is for your MK4 and is constructed of steel with a black finish.
Specifications and Features:
- CMMG AR-15 Receiver Extension M4 55CA9D7
- Compatible with all Mil-Spec diameter stocks
- Hard Coat Anodized Finish
- Matte Black
This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. www.P65Warnings.ca.gov