The device uses a three-color RGB rating system (red, green and blue).

When a test strip is wetted with a urine sample, a chemical reaction, including discolouration, occurs. Different chemical components have different absorbances of the visible spectrum that correspond to a specific test element, so the color change and light reflection are different. High or low reflected light is converted into an electrical signal by a photodetector. Using a three-core RGB (VVA) rescue system, results are stored or selected on the device.