A calligraphy brush that combines both soft and hard hairs is called a Jianhao.
Jianhao (兼毫) means “mixed hair” or “combined bristles.” Its tip blends resilient hair—traditionally weasel, rabbit, or other firm animal hair—with softer hair, commonly goat. The hard fibers help the brush spring back and hold a controlled point, while the soft fibers absorb and release more ink.
This makes Jianhao a compromise between soft-hair brushes, which hold abundant ink but can feel less springy, and hard-hair brushes, which offer sharper control but usually hold less ink. The exact feel varies with the proportion and arrangement of the hairs, so two Jianhao brushes can behave quite differently.
Jianhao is a brush category, not the name of one animal or one fixed size. Brush size is classified separately, and a mixed brush may be sold as small, medium, or large. It is widely used for both calligraphy and Chinese painting, especially when a writer wants ink capacity together with responsive stroke control.