The desired length of the strip can be torn from the roll for a specific application. Most grades have a light, J-weight cloth backing that provides the flexibility needed to conform to circular edges, angles, or other contours. Rolls in grades P50 or P60 have a slightly stiffer X-weight backing suitable for more coarse sanding applications. Cloth remains durable even when bent or rolled, without tearing or shelling, but strips can be torn by hand when a smaller piece is needed, without compromising the sanding surface.
Aluminum oxide is a popular choice among industrial professionals because of its fast cut-rate and long life. This mineral makes a tough, durable abrasive that self-fractures to expose fresh cutting edges, whereas traditional natural abrasives dull more quickly. Aluminum oxide is suitable for a wide variety of materials in both woodworking and metalworking, including ferrous alloys. Aluminum oxide abrasive can be used on ferrous and non-ferrous metals, wood, and plastic.

Dynabrade 13403 Dynisher Finishing Tool, Rear Exhaust, 4,500 RPM, 5/8-11" Spindle Thread
Dynabrade 64863 Variable Speed Versatility Grinder, Slack-Action, 3 hp, 460 V (AC), 3 Phase, 50/60 Hz, 2,000-8,000 SFPM, 1/4"-2" W x 72" L (6-51 mm x 122 cm) Belts 
