Richard Keilwerth was a clarinet maker. According to German saxophone historian, Uwe Ladwig, Richard and his brother Julius had a close business relationship. Richard would provide clarinets to Julius, while Julius would provide saxophones to Richard.

However, not all Richard Keilwerth saxophones were made by Julius Keilwerth. I have seem some made by B&S, Amati, and still others from China or Taiwan. It would appear that only the most expensive of RK's saxes came from his famous sax-making brother.