V Seven Port Door Rod AR .308 Grade 5 Titanium Raw Finish Silver. It does this by slightly adjusting the position of the port door. The Port Door Rod is mounted to the upper receiver with the least amount of force possible. When the rod is straight there is very little side pressure applied to the port door. When the rod is canted there is enough spring force to keep the port door rod in place. The port door does this by applying pressure to the "rod" portion of the assembly and causing it to 'lock' into place. The tip of the port door rod is held in place by the ports small rounded teeth. Due to the hand nature of the AR-15 there maybe some pin/snap securing the port door but be aware pins and such can be difficult to secure in position. Please use your discretion in applying this product to customize your firearm. Specifications for V Seven Port Door Rod: Manufacturer: V Seven Fabric/Material: 6061 Aluminum Condition: New Package Contents: V Seven Port Door Rod What firearm models does the manufacturer say V Seven Port Door Rod is compatible with? The manufacturer says that V Seven Port Door Rod is compatible with AR-15 AR-10 SR-25V Seven PDR-TI308: Port Door Rod AR .308 Grade 5 Titanium Raw Finish Silver