The 81 series of light amber (warming) colour temperature conversion filters decrease colour temperatures and create a warming effect reducing blue casts. These filters are used for more subtle changes in colour balance. They are accordingly often known as light balancing rather than conversion filters. The 81 decreases colour temperature from 3800k to 3200k. This 67mm filter is usable with Hitech 67mm holder systems or any 67mm (2.67″) holder. The filter is also available in 85mm, 100mm, 150mm and 165mm sizes. Hitech filters are made from the highest quality 1.5mm optical resin.