The R-20 is the recommended teeth shade guide for teeth whitening.
The tooth shade chart is used to compare the color of the teeth before and after a teeth whitening treatment. The R-20 is the easiest design for your clients to understand as it is arranged from lightest to darkest

The R-20 because it is strong, easy to clean, and easy to use. Your clients will easily be able to gauge the results with the R-20 Teeth Whitening Shade Guide as it has 20 shades that range from 2 to 40.  Your client will easily see how many shades lighter their teeth have become.  The R-20 Bleaching Shade Guide comes in a quality storage case.