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 26135, PPS Series 2.0 Adapter, Type S40, Trapezoidal Thread, 7100135335
Norton 66261014793 - 3" Medium Grade Aluminum Oxide Bear-Tex Speed-Lok High Strength Maroon TR Non-Woven Abrasive Disc, 80 Each
Norton 66254497067 - 2" X 1/4" 100 - 150 Grit Medium Grade Aluminum Oxide Vortex Rapid Blend Blue TR Non-Woven Abrasive Disc, 25 Each
3M 77197, Scotch-Brite™ Roloc™ Deburr and Finish PRO Unitized Wheel,TR, 3 in x 1/8 in x NH, 8C CRS+, 7100109130, 40/box
Insize 3101-25E, DIGITAL OUTSIDE MICROMETER, IP65, 0-1"/0-25mm, 6928640326783
3M 26110, PPS Series 2.0 Adapter, Type S24, 1/4 Female, R-Angle 18
Thread NPS, Side Cup Mount, 7100135940
3M 07056, Drywall Sanding Sponge CP-042, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Fine, 7100101555 