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.

Norton 66261013403 - 3" X 1/2" Extra Coarse Grade Silicon Carbide Bear-Tex Rapid Strip TR Stripping Disc, 10 Each
3M 01328, PSA Cloth Disc 348D, P180 X-weight, 3 in x NH, Die 300V, 7000045068
3M 34786, 663FC, 3/4" X 90", 70u, Diamond Trizact Belts 7100063667
3M 50258, Roloc Disc 777F, 60 YF-weight, TSM, 3 in, Die RS300VM, 7010325551
3M 07466, Scotch-Brite Roloc+ Clean and Strip Disc 7466, 4 in x 1/2 in S XCS, 7000120779, 10/case
3M 19769, Utility Cloth Sheet 314D, 9 in x 11 in P150 J-weight, 7000000357 
