The Kaiser 4013 Darkroom Light Orange Filter is a 9 x 12 cm red glass or plastic filter designed specifically for the Kaiser 4018 Darkroom Safelight.

An Orange Darkroom filter is a specialised optical filter used in photographic darkrooms to block harmful wavelengths of light. It allows photographers to see their workspace without ruining light-sensitive black-and-white silver chlorobromide paper.

Size 9 x 12 cm (3.5 x 4.7 in.), for 4018 darkroom safelight.

Other Filter options for the 4018 safelight are:
— 4013: Orange, for B&W silver chlorobromide papers
— 4014: Red, for orthochromatic papers and films and B&W graded papers.
— 4015: Amber-colored, for variable contrast papers (Multigrade®) and B&W graded papers