Strike Industries Ultimate Dust Cover, Fits AR-10 in 308, Flat Dark Earth SI-AR-UDC-E-308-01-FDE The SI UDC 308 enables users to attach and detach the cover in 5 to 10 seconds with ease (stock dust cover will take more time to remove)! It is constructed of a high-density polymer making it more durable and functional than the traditional dust covers. The Ultimate Dust Cover features an adjustable detent set screw in order to compensate wear on the receiver and increase or decrease opening power.