JMac Customs Skeletonized Tube with Rise 7in Black. (With proper folding adapter) Some M4 style stocks use tension tabs designed for standard buffer tubes to remove movement. These will work on our Skeletonized Tubes however you may experience some wiggle. Attaching a stock to a pistol makes it an SBR and requires NFA approval. You are responsible for knowing and following your local/state/federal laws JMac Customs LLC is not responsible for the end users misuse of our products. Specifications for JMac Customs Skeletonized Tube with Rise: Manufacturer: JMac Customs Color: Black Length: 7 in Features of JMac Customs Skeletonized Tube with Rise Fits most M4 style stocks/braces. Lightweight and Rigid 0.25 Rise Integrated QD Sling Sockets 7 Length - LOP approximately 8-11.35 inches 7 positions Compatible with our SM adapters FM-SM-1913/MRKT Folding Mech & SIG folding mechanisms Requires a mount or folding mech to install Package Contents: JMac Customs Skeletonized Tube with Rise JMac Customs ST-7R: Skeletonized Tube with Rise 7in Black