The ProGlass ND is an extremely high quality glass ND standard filter optimised for use with digital cameras, but equally useful for film.
This new filter uses a surface coating made from evaporated metal, and therefore provides very even absorption across the visible spectrum and through the UV and Infra Red regions.
Digital SLR users need to use ND standard filters to prolong exposure times in bright conditions for landscape photography, but the excess UV and IR can cause colour problems in some lighting situations. The ProGlass filter reduces any chance of false colour casts, and also provides a result described as punchier on digital and film because the light forming the image is more specific to the requirements of the film or sensor.
A glass filter that reduces exposure by 3 stops without affecting colour balance.