Among hairs from weasels' tail, under jaw,  and fore breast, which are widely used to produce wolf hair brushes, the tail parts are the best and usually for the high end product. Some low price wolf hair brushes are made from mount horse hairs, please read the retail. 
Wolf brushes are relative stiff. 
Some suggestion but not the definition depending on each user's habit and skills
Painting: Good for  Calligraphy and signature for painting, Bamboo, orchid, petals and strokes. Small/script size can be used for ribs of a leaf.
Branch in the method of double sketch/ bone style, such as plum tree. (雙鉤法畫梅幹）.Bill of bird. Stone, mountain, sketch in landscape.
Calligraphy: Good for Regular Script, Official Script 楷書，隸書

Wolf Hairs and other Hard Hairs