Geissele Super Reaction Rod For Ar15/m4 Black. Works by pre-loading the barrel nut extension to the lugs of the Super Reaction Rod to eliminate any movement before adding torque to the barrel nut while at the same time fixing the upper receiver into place. Having the barrel nut extension mated to the Super Reaction Rod lugs and fixing the upper receiver before torqueing will remove any potential stress that could be placed on the index pin. Allows the armorer to place tremendous torque on the barrel nut. Super Reaction Rod's pre-loading system can also be removed to allow it to work just like a standard Reaction Rod which allows upper work to be performed with 360 degree movement both vertically and horizontally. Specifications for Geissele AR-15/M4 Super Reaction Rod: Manufacturer: Geissele Gun Model: M4 AR-15 Gun Type: Rifle Caliber: .223 Remington Color: Black Condition: New Projectile Caliber: .223 Caliber Country of Origin: USA Package Contents: Geissele AR15/M4 Super Reaction Rod The Geissele AR-15/M4 Super Reaction Rod 15-193 is a quality addition to the Geissele lineup. For more great deals on Receiver Vise Blocks & Reaction Rods by Geissele please browse our Geissele Gun Parts page. What firearm models does the manufacturer say Geissele AR-15/M4 Super Reaction Rod is compatible with? The manufacturer says that Geissele AR-15/M4 Super Reaction Rod is compatible with AR-15 M4Geissele 15-193: Super Reaction Rod For Ar15/m4 Black