Correct color balance makes excellent photoes.
Gray card works with any film and digital camera and can balance all mixed lights to be 18% neutral.
Controlling the gray balance in digital photography, Grey Card can balance light and measure the exposure of camera.
Correcting white balance, White Card can correct white balance and get uniform neutral light.
Blocking stray light of lens, Black Card can even screen light in long exposure.

Card size: 3.35 X 2.2 inches (8.5*5.4cm)

Package Contents:
1 x grey card (8.5*5.4cm)
1 x white card (8.5*5.4cm)
1 x black card (8.5*5.4cm)
1 x detachable lanyard strap