This is a 6 part pipe over-grainer. It is used to create the shaped grain found in hardwoods such as mahogany, maple, and walnut. It is referred to as a piper over-grainer because of the way the bristles are clumped together on the brush.
Maire, F. Modern Painter's Cyclopedia (Chicago, IL: Frederick J. Drake & Company Publishers, 1918)
Courtesy the private collection of Roy Winkelman