Typical Paper Charts vs. WaterColors
Most aquarists are familiar with well-known paper charts for comparing water test results, like this one from API.
WaterColors Is Different
The WaterColors Test Chart contains five separate charts in one download: Ammonia, Nitrites, Nitrates, Low pH, and High pH.
Each individual chart is a high quality jpg photo of actual test tubes.
The downloaded charts can be viewed on any device. Just zoom in to get a closer look at the colors.