The Tune-a-Flex element from Elk Industries LLC acts as a color filter. It looks like an ordinary piece of glass but, when held up to a light, “filters” light into a red color. When the plate is tilted, from one angle to another and in the same plane, it changes color from deep red to bright green. Guaranteed efficiency is >90% and, typically, ≥95%. There is no refractive activity to cause problems for imaging applications. Five types cover five spectral ranges, which can accommodate the entire visible wavelength range, with some overlap. With Tune-a-Flex, a single element can be used to allow narrow-linewidth tuning with high efficiency. For use in polymer or polystyrene dye lasers, it affords the user a greater range of applications than the typical broadband outputs available without a tuner.