These  acrylic filters allow transmission with less distortion and more durability than plastic or gelatin filters.  Use with a hand held spectrometer for absorption experiments, with slide projectors for color addition experiments, or in Young's Double slit experiment to measure the wavelenfth of different colors of light.  A set of five filters (red, orange, yellow, green, and blue).  Dimensions: 2" x 2" x 1/8".