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.

3M 22405, Roloc Disc 361F, P100 YF-weight, TR, 3 in, Die R300V, 7000045102
Dynabrade 78127 3" Dia. Medium NWN VT DynaBrite Locking-Type Disc, 25/pack
3M 87449 Silver Depressed Center Grinding Wheel, T27 Quick Change, 9 in x 1/4 in x 5/8-11 Center Hub Thread, 7010409732, 20 per case
Norton 66261014921 - 2" X 1/8" 50 - 80 Grit Coarse Grade Aluminum Oxide Bear-Tex Speed-Lok Rapid Blend Gray TR Non-Woven Unified Wheel, 60 Each
3M 01326, PSA Cloth Disc 348D, P240 X-weight, 3 in x NH, Die 300V, 7000045069
Dynabrade 11254 Contact Arm Ass'y, 4-3/4" Dia. x 1/2" W
Dynabrade 96101 Dynabrade Air Lube 10W/NR 24 Per Box
3M 22392, Roloc Disc 361F, 24 YF-weight, TR, 3 in, Die R300V, 7000045090
Standard Abrasives 78513, Ceramic Pro Type 27 Flap Disc, 645110, 4-1/2 in x 7/8 60 Y-weight, 7010369540, 10 per case 
