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 98270 1/2" Male Coupler
3M 03126, General Purpose Sanding Sponge CP040-6P, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Fine, 7100101532, 6/pack
3M Scotchkote Liquid Epoxy Coating Spray System HSS Mix Nozzle, RightAngle, 7000058900 
