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 45014, Diamond Grade DG3 Reflective Digital Sheeting 4090UDS, White, 30 in x 50 yd, 1 Roll/Case, 7100282804
3M 26022, PPS Series 2.0 Adapter, Type S12, 10 mm Male, 1.0 mm Thread, 7100135943
Dynabrade 97571 1/2" NPT Male Safety Coupler
3M 26118, PPS Series 2.0 Adapter, Type S26, 11 mm Male, 1.0 mm Thread, 7100135924
3M 07056, Drywall Sanding Sponge CP-042, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Fine, 7100101555 