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?).

3M 65490, Pro Grade Precision Ultra Durable Universal Hole Sanding Disc, DUH580TRI-10T, 5 IN x UH, 80, 7100202914, 10 per pack
3M 22409, Roloc Disc 361F, P120 XF-weight, TR, 1-1/2 in, Die R150S, 7000045103
Dynabrade 78190 2" Dia. x 36 Grit A/O DynaCut Locking-Type Disc, 2 Ply Cloth, 25/pack
Insize 0130-L110, LIGHT METER (BASIC TYPE), 6974029776564
3M 07054, General Purpose Sanding Sponge CP-041-ESF, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Medium, 7100101551 