The new wave HI-PER GREEN discs was designed to overhang the appropriate backup or innerface pads. This overhang prevents the edge of the discs from making lines in the inside curvature of the bowl. The disc is made of HI-PER GREEN "J" weight paper and backed with Hoop & Loop material. There is a serrated coating on its surface ro reduce loading and clogging. This product is second to none on all turnings whether using a Sorby Sandmaster or power sanding with an elctric drill.