Optimo Kolinsky Sable brushes are made with a perfect combination of the best male and female sable hairs available. Kolinsky Sable hairs (named for the Kolinsky mink found in Siberia from which the hair is taken) are widely recognized as one of the best types of hair for watercolor due to its softness and natural spring. Acrylic and oil painters use them to paint portraits or to add final details to a piece. These brushes are expensive and should be treated as a treasured tool.