Princeton Grainer 3/8 “ Mini Detailer Taklon Watercolor Brush. (Grass Brush)

Mini-detailer. Series 3050.

Precise brushes for precise tasks. Superb for fine detail painting. Sought-after by decorative artists and painters of miniatures in watercolor, acrylic, and gouache. Wooden handles are finished in a comfortable silicone allowing a firm grip and ultimate control. The finest synthetic sable, assures a perfect point and crisp edges on flat shapes.

This  brush is especially nice for grasses and feathers.  
Also referred to as a grass brush