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 87449 Silver Depressed Center Grinding Wheel, T27 Quick Change, 9 in x 1/4 in x 5/8-11 Center Hub Thread, 7010409732, 20 per case
3M 71361, 641WY 1/4" X 24", 1200 Mesh Diamond Cloth Belt, 7010534916
Insize 4102-136, STEEL GAGE BLOCK SET, 36pcs, grade AS-1, 6928640329876 