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 27256, Ultra Durable 5 inch Power Sanding Discs, Universal Hole, 220 grit, 7100188465, 5 per pack
3M 35083, EMI Copper Foil Shielding Tape 1181, 1/4 in x 18 yd (6,35 mm x 16,5 m), 7000132168
3M 26173, PPS Series 2.0 12-Pack Refill Kit, Standard (22 fl oz, 650mL), 200 Micron Filter, 7100166278 