Verify the performance and accuracy of your spectrophotometer right in your own lab. These permanent standards do not have to be recalibrated due to material aging. Unique material construction is scratch resistant and provides stable optical performance. Photometric Accuracy and Stray Light Calibration Wavelength Kit 02660-04 is a comprehensive set to use for UV-VIS photometric accuracy, absorbance accuracy, stray light (200 to 700 nm), and wavelength accuracy in the UV and visible range (200 to 700 nm). The wavelength accuracy filter is made from holmium oxide and has ten NIST-certified calibration peaks. The UV photometric accuracy filter is made from didymium and has five NIST-certified calibration peaks and five photometric calibration points in the UV range.