The Wheeler Engineering AR-15 Upper Receiver Action Rod is designed to eliminate stress on the upper receiver when installing a new barrel. Simply insert the Action Rod into the upper receiver, then slide the gas port indexing rod inserts through the upper receiver to align the barrel nut. Next, turn the rear twist lock, which will activate the front locking bolt to hold the barrel secure. Finally, clamp the rear of the Action Rod into a vise to remove stress on the upper receiver. The Upper Receiver Action Rod works on all AR-15 barrels with standard barrel extensions. No need to remove sights or optics. FeaturesCompatible with all standard AR-15 Barrel ExtensionsEliminates Upper Receiver StressEasy Installation