FLEXCEL Type 27 and Type 29 Semi-Flexible Wheels can remove material aggressively like a grinding wheel, and blend and finish like a sanding disc. FLEXCEL wheels flex to contoured surfaces giving a smooth finish without gouging. Faster stock removal than standard depressed center wheels. Will not load on aluminum and soft metals. For general purpose applications, grinds aggressively like grit 24 sanding disc, and finishes like a 60 grit disc. Type 27 shape's flat grinding face is preferred for smaller contact area.