Improve the consistency of your DSLR camera's color photos with this ExpoDisc 2.0 EXPOD2-77 77mm lens filter, which lets you set white balance, meter 18% incident exposure and dust map your camera's sensor to ensure images with a high level of quality.
I love this so much!! I used to use a gray card but it was bulky and alward to carry around. This fits in my pocket and it super simple. One tip I learned is to get your exposure correct before you white balance and you will be good to go! I have recommended this to so many people!