A universal multifunctional cover for a quick-acquisition optical sight in the form of a box-like casing with an open front end, which in the sight-closing position of the cover is located in front of the optical lens, and with a rear end closed with a transparent medium. The cover is provided with a frame that supports an optical filter and has a radial outward projection that can be used as a foresight. The frame is pivotally supported by stretchable resilient members such as rubber strings so that the frame with the foresight and the filter can be switched between the following three positions: a first position in which the frame rests on the box-like casing, a second position in which the frame is installed in front of the optical lens with the foresight projecting upward, and a third position in which the frame is installed in front of the optical lens with the foresight projecting downward and closing the sensor.