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 83539, Scotch Heavy Duty Packaging Tape Dispenser ST-181, Foam Handle with Retractable Blade, 7100288393
Dynabrade 77758 4-1/2" Dia. x 7/8" Center Hole, 60 Grit, Z/A, Type 27, DynaCut Flap Disc W/Fiberglass, 10/pack
3M 65488, Pro Grade Precision Ultra Durable Universal Hole Sanding Disc, DUH5100TRI-10T, 5 IN x UH, 100, 7100202881, 10 per pack
Dynabrade 90874 2" Dia. Very Fine NWN DynaBrite Locking-Type Disc, 25/pack 