Features:
Includes four color calibrated reference cards: white， black， neutral gray， blue cards.
It helps you get correct white balance， or color balance， allowing the camera to compensate for the illuminant color in a scene.  
For optimum color correction: the black card achieves truly deep blacks (RGB 16，16，15); the grey card displays superior spectral neutrality with measured values of 162， 162， 160; the white card has a tested RGB value of (220， 224， 223). 
Use with any digital camera. 
Lanyard strap included.
The neck strap with quick-release plastic buckle on the end， convenient for your use. 

Specifications: 
Color of the Cards: White， Black， Grey， Blue
Size: 13 * 9cm / 5.1 * 3.5in 
Weight of 1 Card: 16g / 0.6oz 
Package Size: 13 * 9 * 2cm / 5.1 * 3.5 * 0.8in 
Package Weight: 88g / 3.1oz 

Package List: 
4 * Grey Card 
1 * Lanyard Strap