CameraTrax 24 ColorCard 4x6 with 12 percent White Balance Card and User Guidebook Large 4x6-in 24ColorCard with GreyCard conveniently mounted to the reverse side Precision 12%-Grey reference for white balance plus 24-Color patches with RGB values for superior digital color correction Double-sided construction, archival quality acid-free materials and color printed User's Guide Detailed instructions included for Picasa 3.8, Photoshop Lightroom 3, Photoshop Elements 9.0 and Photoshop CS4 This is the 4x6 size of the CameraTrax 24ColorCard family: 2x3, 4x6 and 3x5 (OneSnapColor)