Geissele AR-15/M4 Reaction Rod Steel 223 Rem 5.56x45mm NATO AR15/M4/M16. The Reaction Rod is designed to be gripped in a bench vise so that the rod is either horizontal or vertical. Specifications for Geissele AR-15/M4 Reaction Rod: Manufacturer: Geissele Finish: Black Gun Model: M4 AR-15 Gun Type: Rifle Caliber: .223 Remington Fabric/Material: 4140 Chrome Moly Steel Color: Black Condition: New Projectile Caliber: .223 Caliber Country of Origin: USA Quantity: 1 Package Contents: Geissele AR15/M4 Reaction Rod The Geissele AR-15/M4 Reaction Rod 10-169 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 Reaction Rod is compatible with? The manufacturer says that Geissele AR-15/M4 Reaction Rod is compatible with AR-15 M4Geissele AR-15/M4 Reaction Rod