ShootSmarter

The 20 inch BalanceSmarter:
Studio shooters, and the outdoor portrait photographers seem to like the standard 20 inch version because it’s just big enough to fill the viewfinder using most lenses, it’s very easy to carry with you, and subjects can hold it easily for terrific in-studio or fill flash outdoor color.

What is a BalanceSmarter?
It’s a popup panel that comes in 3 sizes that you "take a picture of" to activate the custom white balance function (Also called PREset white balance in the Nikon world) of your digital camera. Each BalanceSmarter has a digital neutral white on one side and a digital neutral grey on the other.

Can you see the center mark in the middle of each panel? That's for your autofocus to grab onto so you no longer have to fuss with turing your autofocus off and on again to make a custom white balance.