Accuracy: ?2″.
To inspect protractor, taper gage, index plate, index head and goniometer, can also be used to set angle.
Made of special alloy steel, hardness HRC64, high stability, wear resistance and easy combination.
Can be combined to any angle with interval 6 seconds after combination (6″, 12″, 18″, … , 360?).

Norton 66623335427, 2" Dia Vortex Rapid Prep Quick-Change Non-Woven Abrasive Disc, Medium Grade, 50 Each
Insize ISF-DF500A, DIGITAL FORCE GAGE (HIGH RESOLUTION), 110lbf, 6928640326011
3M 37024, Extra Large Drywall Sanding Sponge 910-DDA, Dual Angle, 2-1/2 in x 8 in x 1 in, Fine, 7010375249 