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?).

Dynabrade 78579 1/4" Dia. x 1" W x 1/8" Center Hole, 60 Grit, 100/pack
3M 54762, SandBlaster Quick Change Hub for Right Angle Grinder 9675, 4.5 in, 7010301728 