The patent pending SI UDC enables users to attach and detach the cover in 5 to 10 seconds with ease! 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 (To adjust detent: use small flathead driver and depress the ball detent and adjust as necessary.). Choose multiple designs to customize your AR!