This item is a older non F-Pro series Filter. Same Standard SC coated product. Exposed filter ring depth of this filter is 5mm versus the 4mm of the F-Pro Series

TheB+W KR3 (81C) Filteris a color conversion filter that helps to slightly decrease color temperatures and provide a warming effect. The 81C filter adds more warmth to the image for use with tungsten films in natural lighting. It provides a decrease of 400K, helping to render the scene more similarly to incandescent illumination.

There is a 1.5x filter factor with this filter, requiring an increase of 0.6 stop for normal exposure. B+W filters are constructed from high quality Schott glass for increased optical clarity and color fidelity. They feature a brass filter ring for durability as well as jamming prevention.
Color conversion filter helps to slightly decrease color temperatures and provide a warming effect.
Provides a decrease of 400K for use of tungsten-based films in daylight situations.
Constructed from high quality Schott glass for optical clarity.
Brass filter ring helps to prevent jamming and provides additional strength.

PRODUCT HIGHLIGHTS
81C Filter for Color Conversion
Warming Filter to Decrease Color Temp
Single Coated Schott Glass
Rugged Black Brass Filter Ring

Type: Warming filter
Size: 62mm
Grade: 81C (KR3)
Filter Factor: 1.5 (0.6 stop)
Single-Coat
Effect: Provides decrease in color temperature for warming effect
Application: For use with tungsten-balanced film outdoors
Color Temperature: -400K
Construction: Schott Glass
Front Filter Thread Size: 62mm
Front Lens Cap Size: 62mm