Polished Brass Rock Slides have huge sustain. Why so much sustain? Because the heart of The Rock Slide is the solid brass rod that is CNC carved to fit your finger. This particular brass formula is very heavy which is the best for tone and sustain. The walls are thick and get thicker towards the end of the slide because of the internal taper design. We intentionally added a tone ring at the fingertip end which adds mass and helps secure your finger. Like a Hawaiian tone bar cuts through the mix with more weight and mass, so does The Rock Slide.