The gen-ii pro series is an evolution of the m4 model, adding a 7.8" free float aluminum forend with 8 position picatinny rail.All other characteristics remain unvaried: 18.5" heavy match, parkerized barrel, steel bolt, mil-spec components.It is available with a 10 or 28 round magazine.Metal Finish: BlackAction: Semi-AutoCaliber: 22 LRBarrel Length: 18.50"Capacity: 28+1Trigger: StandardSafety: ManualOal: 34.30"Weight: 5.70 lbsStock Description: 6 PositionMuzzle: Flash SuppressorReceiver Material: PolymerSights: None, Optic ReadyBarrel Description: SteelTwist: 1:16"Barrel Length Range: 18" to 18.99"Weight Range: 5 lbs to 5.99 lbsHand: RightStock Finish Group: BlackMetal Finish Group: Blued/Black