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 45015, Diamond Grade DG3 Reflective Digital Sheeting 4090UDS, White, 24 in x 50 yd, 1 Roll/Case, 7100282694
3M 34425, General Purpose Sanding Sponge CP041-3PK, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Medium, 7100175218, 3/pack 