Optolong's UV-IR cut filter is designed to block ultraviolet and infrared wavelengths to improve sharpness of the image as most of the optics are designed for the visible spectrum | because it's very difficult to create a lens with the same focal point for the visible and IR spectrum | It is used on a digital camera and the video, which do not have an IR protection filter toward an image sensor or were remodeled. | This is important because unfiltered CCD and CMOS sensors are extremely susceptible to UV and IR rays just outside the visible spectrum that can have a very negative impact on image quality