This super-soft sanding pad is used for shaping foam and CNC surfboard shapes in production, it is by far the softest sanding pad made today. It's so soft it will roll rails with hardly any ridges, take out planer tear and CNC ridges quickly. (beware: keep this pad spinning under 750 RPM or it won't last) Maximum RPM: 750. 5/8-11 female threaded Hub