Eraser Wheel has serrations for improved cooling effect air flow.
Dynabrade surface grinding wheel has a diameter of 4 in. The quick change attachment allows for easy mounting to the tool or pad. In addition to the other aspects of these parts, another important component of these is the thickness. This Dynabrade part is 1 1/4 in thick. All abrasive products that rotate or spin, such as the ones in this category, have a maximum speed at which you can run them. This Dynabrade surface grinding wheel can be run at a maximum speed of 4000 RPMs.

Dynabrade 14000 Dynafile Abrasive Belt Tool
Dynabrade 53270 7" (180 mm) Dia. Right-Angle Disc Sander
3M 77558, Cubitron II Hookit Cloth Disc 947A, 77558, 40+ to 120+, 6 in x NH, Die 600Z, 7100232737
3M 22396, Roloc Disc 361F, 36 YF-weight, TR, 1-1/2 in, Die R150S, 7000045091 
