The JJC Grey Card 3-in-1 Set is perfect for basic colour management on location or in the studio. Managing the colour and white balance while shooting portrait work or events and weddings, is crucial in saving time in post processing. This 3-in-1 set contains an 18% reflective grey card and white and black point reference cards. This would allow you to set your white balance appropriately as well as your levels and contrast range (based on the white and black cards). The set is credit card size and fits in your pocket perfectly so you can take it with you and have it handy on every shoot. They are bound together on a keyring and attached to a lanyard so you can loop it around your belt or camera strap.