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 95843 Dynabrade Air Lube 10W/NR, 1 Gallon
Dynabrade 51332 .7 hp Router, 3-1/2" Base, Central Vacuum, 20,000 RPM, 1/4 Collet
3M 76631, Roloc Disc 777F, TR, 3 in x NH, 36 YF-weight, 7000028339
3M 19766, Utility Cloth Sheet 314D, 9 in x 11 in P240 J-weight, 7000000354 
