The Crescent 10" File Card and Brush, part 21467. Supplier specification: 10" CARD/BRUSH.
Two things decide a file: cut and coarseness. Single-cut leaves a smoother finish and is what draw filing needs; double-cut removes material faster and leaves a rougher surface. Coarseness runs bastard, then second, then smooth. Start coarse to shape and finish fine — and fit a handle, because a bare tang is the most common file injury.
