All three of these mallets use a unique brass core to enhance the fundamental tone. The DD20R is designed for use on orchestra bells, and work particularly well on wide bar bells. The 20R is a great general purpose bell mallet that produces a big sound with lots of fundamental tone, yet is still light enough for playing faster passages.
Doug DeMorrow is a respected percussion instrument maker and performer. Doug attended North Texas University for graduate school where his interest in the acoustics of the marimba bar led to a project, thesis, and ultimately the construction of a three-octave prototype marimba, currently on loan to Henderson State University.