Ares VZ58 Side Scope Mount Rail Colt M4A1 and in this case

and in this case

- Length: 530mm / 685mm (Extented)

Nozzle and Hard Piston with 7 Metal Teeth  Metal Piston Head w/ Bearings  Cylinder For 301 - 400 mm Inner Barrel  Durable Tappet Plate  Metal Anti-reversal Latch  Spring Guide with Bearings  M135 Spring  Completed Gearbox set ready to upgrade  Anti-Heat & Anti-Wearing Construction  Suitable for AEG brand: King Arms & Other Compatible M4 / M16 Series AEGs  As always

Titanium carbon nitride (TiCN) coating is used on the finishing to reduce the galling and friction

Ares VZ58 Side Scope Mount Rail Colt M4A1 and in this caseOn the left side of the VZ58 receiver is a slot for the Side Scope Mount Plate which in turn will allow you to slide on a Side Scope Mount Rail so you can add any sight you prefer to it.