Olight Filters and Diffuser fit Olight M20 Series Lights as well as many other similar sized lights.
Green light is preferred by hunters and fishermen because it is a very soft light that will not spook their prey. Green also does not attract insects like white or yellow light does. It is not easily picked up, unless looking directly at it, so it is useful in covert operations. It is also useful in smoke or fog filled environments. Green is also very popular for night time map reading.