Designed for CCD astrophotography, the set includes Luminance-IR, Red, Green, and Blue dichroic CCD filters. The filters are resistant to humidity and scratching and set into a durable aluminium alloy threaded mounting ring. The red green and blue filters have been developed to closely match the natural colours of stars, planets and emission nebulae, whilst the luminance filter removes damaging haze and ultraviolet. The filters offer light transmission of nearly 100%. Please note the red, green and blue filters are not IR coated.