The SI-AR-ALUDC-223 takes everything you love about the polymer UDC’s to the next level. With an all-aluminum construction and CED coating for added durability and a cleaner finish, the Aluminum UDC is the modern evolution of standard mil-spec dust covers. It features an adjustable detent set screw in order to compensate wear on the receiver and increase or decrease opening power. The aluminum UDC still uses the unique installation system that enables users to remove or install in under 10 seconds flat! But the most notable difference is the patent pending noise-reduction padding that makes it nearly 100% silent during activation!