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 02545, Gold Abrasive Sheet, P180 grade, 9 in x 11 in, 7000118284, 50 sheets per pack
Dynabrade 25234 Vane Set (4pk)
Air Turbine Tools 2545SVF - 1/4" Angle Hand Tool Series (Long Version, Front Exhaust), 40,000RPM, 35542
Dynabrade 11395 Guide Wheel 
