The CameraTrax OneSnapColor FlipCard design, with invisible magnetic latch, is a snap to open, close and use. The outside is laminated to protect the precision 24Color and 12% Grey cards inside. At 3.25 x 4.75 inches [82x120 mm], the OneSnapColor card easily slips into a pocket or camera bag and just at 2 ounces [~60gramsgrams... ], you can take it everywhere. The FlipCard design gives quick access to both Grey and Color cards at the same time. ITS EASY to improve the color of your photos in 3 simple steps: 1) white-balance your camera using the Grey side, 2) Photograph the Color side and then photograph your subject and 3) use the auto-adjust features of your photo software in your computer. asa (Free from The Users Guide also includes discussion of color balance theory and an additional section for advanced users. 2x3 card Note: Like all quality photographic color references, the colors are not plastic-laminated (which would damage color accuracy) so do not let the colors get wet. The Users Guide is an integral part of the product so is not available as a free download. are designed and manufactured in Other card sizes include: -2x3 (2x3-in [50x76mm]). QUESTIONS: You can always email info at CameraTrax.com .