Very Important: Inside the black envelop, you get a QR code INSTALLATION INSTRUCTION card please see the video before start using the product. Installation: Now switch your filter in 2-3 seconds with Freewell Quick Swap Magnetic system no more threading Optical Glass: Made using the High Definition Premium Optical glass double-side multicoated Zero chromatic aberration (color shift) Function: Helps during night-time photography as it helps to capture crystal-clear and sharp images of the night-sky by effectively preventing the surrounding light pollution from affecting your picture quality. What is Included: Empty Magnetic Base Ring, Light Pollution Filter, Lens Cap, Microfiber Cleaning Cloth, Storage Case