6 inch hand-pattern smooth file at 152 mm. Parallel-edge hand file with one safe edge, used by machinists and fab shop techs for finish work on flat surfaces.
Knife bastard file at 6 inches, 152 mm. Knife-edge profile gets into narrow slots and acute angles for stock removal in fabrication and machine shop work.
6 inch three square smooth file at 152 mm. Triangular cross-section with fine cut, used for sharpening saws and filing acute angles in fabrication and shop work.