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?).

ACS Diamond Grinding Disc, 4-1/2" Dia. X 5/8"-11 Center Hub Thread, Type 29, 36 Grit
3M 33446, Cubitron II File Belt, 80+, 1/2 in x 18 in (12.7 mm x 457.2 mm), 7100033186, 10 belts per carton, 5 cartons per case 
