The HR* CUSTOM DARK is our premium line of hard rubber saxophone mouthpieces, where the goal was to make the most beautiful sounding and playing pieces that we possibly could. As alto sax players, we know there are often a lot of unpleasant highs in the sound, especially on the higher notes. With the HR* CUSTOM DARK Alto, we retained the fun of playing a great alto mouthpiece while taking all the unpleasant highs off, by shaping a beautiful rollover baffle which gives it the pop and feedback that alto players are used to and then making a big large chamber and bore to give it this mellow, warm pretty sound.