第1代SOPMOD M4 的主要承包商是KAC 公司， 主要模块包括一个有上下左右四段M1913 标准 导轨的 RIS 护木，安装在柯尔特公司生产的重型枪管 M4A1 上。 其他的部件还包括截 短了枪管的快卸M203A2榴弹发射器及其瞄准具、一个KAC 快速拆卸（QD）消声器、 KAC后备照门、一支战术灯、一个AN/PEQ-2可见光/红外激光指示器，还有Trijicon的ACOG和反射式瞄准镜及一个夜视瞄准镜，但也有许多士兵把Trijicon反射瞄准镜换成M68 CCO或EOTech全息瞄准镜。 SOPMOD …

The Daniel Defense Rail Interface System (RIS II) was designed at the request of the United States Special Operations Command (SOCOM) for the SOPMOD II program. SOCOM had a specific requirement for a free float M203 solution and Daniel Defense responded, designing a revolutionary product to meet the government’s need.

The M4A1 AR15 style firearm features the RIS II picatinny quad rail, which has been in use by US Special Operations Command (SOCOM) for the SOPMOD Block II program since 2005. The M4A1 is built around a 14.5 inch Cold Hammer Forged M4 Profile barrel with a permanently attached Daniel Defense Flash Suppressor.

The Daniel Defense RIS II free-floating Picatinny rail systems are designed to allow individual operators to quickly, and without special tools, mount the M203 Grenade Launcher and precisely mount SOPMOD accessories to host weapon without effecting point of impact.

A machined aluminum multi-rail handguard specifically designed for the Special Operations Command (SOCOM) M4A1 carbine, the RIS II enables installation of an M203 40mm grenade launcher, while allowing the barrel to free float. The M203 attaches to the bottom rail quickly and easily, without special tools or additional parts.

美国陆军特种作战司令部已经决定将采用URGI（upper receiver group-improved，改进型上机匣组），URGI将取代USASOC现役的BLOCK II M4A1 URG，作为未来的主力卡宾枪。 比起BLOCK II URG，URGI的改进之处在于：1、将…

The Daniel Defense M4A1 Rail Interface System RIS II is not compatible with an Aero Precision M5 upper. This rail is designed for AR15 pattern receivers, not DPMS pattern. by Ethan, Gear Expert, October 7, 2022

Series/Collection: M4A1 RIS II; Material: 6061 T6 Aluminum; Finish: Hardcoat Anodized; Color: Black; Length: 12-1/4" Width: 2.23" Height: 2-1/4" For Use With: AR-Platform Rifle; Weight: 17.7 oz; Inside Diameter: 1.15" Gas System: Carbine

Inspired by the USSOCOM SOPMOD Block II, the Daniel Defense M4A1 FSP Upper Receiver Group is designed for enthusiasts who demand military-grade precision and performance. This upper features the M4A1 FSP RIS II Picatinny quad rail in a striking Flat Dark Earth finish, paired with a 14.5" M4 profile barrel and a Mil-Spec F-marked front sight base.

The Daniel Defense RIS II allows the individual operator to free float the M203 grenade launcher without additional parts. As importantly, special tools are not required to mount the M203 grenade launcher. This was accomplished by integrating all of the needed parts to …