This is a Daniel Defense Rail known as the Omega, model 01-005-10002.
Daniel Defense's OMEGA 9.0 Mid-Length Rail system is the most exciting rail system to hit the market in years! The Omega Rail is a free float rail system that allows the individual operator install it with the Allen Wrench provided and requires ZERO modification to the weapon! The Omega Rail features an integral QD sling swivel mount" with rotation limiter" and an uninterrupted upper rail platform. This light weight rail system is meticulously CNC machined from Aircraft Grade Aluminum and is Military Specification Type III Hard Coat Anodized. All the Omega Rail fasteners are military specification. The Omega Rail 9.0 is designed to work with Mid-Length AR15 gas systems.
Features:
No modification to host weapon
Integral QD Sling Swivel Mount with limited rotation
Continuous upper rail with upper receiver
Removable Lower Rail