Norton 03227 Hook & Sand 5 Inch Universal Fits 5 And 8 Hole Cerma Alumina Sanding Discs have P-graded seeded-gel ceramic alumina. These sanding discs have a laser-cut vacuum hole design giving them a long life and the water-based, non-pigmented stearate avoids color transfer to your workpiece while minimizing load. They are a great choice for fine grit vacuum sanding and finishing.