AbstractIn 1983, a new supply of didymium glass filters was prepared since the stock calibrated in 1976 has been very useful for wavelength calibration and the inventory has been depleted. Results for representative samples of the new filters are presented. The new supply of glass has been calibrated by the batch mode and will be designated Standard Reference Materials (SRM) 2009A and 2010A. During the latter part of 1976, research was begun to characterize didymium glass filters for use with visible spectrophotometers with bandwidth in the range 1.5 to 10.5 nm. These filters were found to produce a smaller wavelength uncertainty than previously issued filters. Also, it was found that points of inflection in the transmittance curve could be used to supplement the data for transmittance minima. The results of that research were SRM 2009, 2010, 2013, and 2014. The same techniques were applied in 1983. Also, the results from 1983 and 1976 for one of the Master filters are compared.