Purchase here a modern incarnation from Danmar of the old-style muffler for the bass drum, which you mount on the front hoop. From there, the "arm" extends down in front of the bass drumhead, allowing you to control the amount of overtones from the bass drum's front head.
Danmar's 920 'clamp-on bass drum muffler' is solidly built, so even though the concept is old, the product's quality is modern and robust - "made in the U.S.A.".
The muffler consists of a large felt pad that, when in contact with the front drumhead, regulates the amount of 'ring' or overtones. This allows you to control your bass drum's sound externally, which can be a significant advantage, especially when quickly adapting to the venue you are playing in.