Vidpro 5x7 Inch White Balance Card Set (Includes Grey, White & Black Reference Cards)
The Vidpro White Balance Card Set for Digital Photography is an excellent tool for achieving perfect color balance and accurate exposure  in your photos. You can use it under any lighting condition, both pre- and post-production. This set includes an 18% neutral grey card, a pure white card , true black card, and a detachable lanyard that will keep it handy at all times.