The 3M Hookit II Soft Interface Pad is placed between the abrasive disc and backing pad. Constructed of a soft durable foam, 3M's Hookit II Soft Interface Disc Pad makes sanding contours and edges much easier and provides a more uniform result. The 3M Hookit II Soft Interface Pad has 6 dust extraction holes, but works extremely well with non-dust free discs as well.