Filters made by various manufacturers may be identified by Wratten numbers but not precisely match the spectral definition for that number. This is especially true for filters used for aesthetic (as opposed to technical) reasons; for example, an 81B Warming Filter is a filter used to slightly "warm" the colors in a color photo, making the scene a bit less blue and more red. Many manufacturers make filters labeled as 81B which do similar but not exactly the same filtering of light, according to that manufacturer's idea of how exactly it is best to warm a scene, and depending on their manufacturing techniques. Some manufacturers use their own designations to avoid this confusion, for example Singh-Ray has a warming filter which they designate A-13, which is not a Wratten number. Filters used for printing press color separation or scientific photography tend to have less variation.

Wratten filteroptometry

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Wratten filterfor slit lamp

Teng Tools also offers system trays with three-color EVA inserts that make it even clearer if a tool is missing. All parts are compatible with each other and the user can easily plan and adjust the placement of the tool kits in their storage solution.

The value of having hand tools in order is vital to the industry. The tools must always be in the right place at the right time to ensure the quality of the work to be performed. Teng Tools has, therefore, in close collaboration with its end customers, developed the ‘Get Organised’ concept, with the LEAN principle in mind.

The concept consists of stationary, mobile and portable storage solutions that in combination with hundreds of tool kits create a modular scalable system for hand tools. The tool kits are delivered in system trays with a clear location for each individual tool, which is clicked together and placed in the storage solution.

They are named for the man who founded the first company, Frederick Wratten, a British inventor. Wratten and partner C. E. K. Mees sold their company to Eastman Kodak in 1912, and Kodak continued to produce "Wratten Filters" for decades. Even now, as of 2006, Wratten filters are still produced by Kodak, and sold under license through the Tiffen corporation.