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Knight's Armament Co URX 4 Free Float Rail System for M4 / M16 Series Airsoft AEG Rifles - 10" / Black

ID: 53770 (RIS-KAA-URX4-10)
4.0 stars, based on 2 reviews
Knight's Armament Co URX 4 Free Float Rail System for M4 / M16 Series Airsoft AEG Rifles - 10 / Black
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MAP ProtectedExempt From Coupons
The manufacturer of this product enforces a strict minimum advertised price (MAP) policy which excludes this product from any additional discount coupon codes. This item, however, may qualify for free shipping.
The KAC URX 4 Rail is a fully modular design that utilizes the revolutionary KeyMod accessory mounting system. The URX 4 Rail is stronger and more stable than previous URX designs due to its one piece construction. It is also lighter due to its Integral Barrel Nut (IBN) system of attachment. The IBN system allows the rail itself to act as the barrel nut when torqued onto the rifle, completely eliminating the need for a separate steel barrel nut. KeyMod accessories may be mounted anywhere along the URX 4's length, making it one of the most user configurable designs on the market.


  • Fully licensed by Knight's Armament Company
  • Made from CNC milled aluminum
  • Matte black anodized finish
  • 20mm Picatinny top rail
  • Compatible with airsoft spec. KeyMod systems
Length: 10"
Compatibility: For Tokyo Marui, Matrix, G&P and other compatible M4 / M16 Series Airsoft AEG Rifles
Material: CNC Milled Aluminum

Manufacturer: Knight's Armament Co.

2 Customer Reviews

(Write a review)

by Anthony T. on 10/31/2016
"Fits as expected and is very simple to install. Literally twist it onto the receiver and use the shims to find the proper timing, just as the previous user posted. Others may complain of the keymod being cheaply executed (which is the case, no inner beveling), however I've attached BCM accessories to it with no incident. For the price and weight, thumbs way up...
by Tuan T. on 07/01/2016
"Nice quality Keymod Rail System. It came with extra barrel washers for timing the rail to the upper receiver. Would definitely recommend for rear wired guns only. I installed it on a front wired gun and had to do some major modification to the wiring, but not the rail system's fault

Light weight and minimalist
Finish is good
Barrel shims make it easy to tighten and match up with rail on upper receiver.

No real cons unless installing on a rear wired gun.

Definitely recommend this product.

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