A 105mm (Coarse Thread) Light Yellow #6 Filter from Tiffen is used for a slight increase in contrast with black and white films. Although not as strong as a traditional Yellow #8, it can still be used to make a difference in your photography. You'll find it boosts your contrast just enough to make the difference between a black and white print flat appears "flat" and one that displays the proper correction.

Tiffen's ColorCore glass is produced through a process that entails permanently laminating the filter material in between two pieces of optical glass that are ground flat to tolerances of a ten-thousandth of an inch, then mounting them in precision aluminum rings.