T12 carbon steel nut seating file

185mm long by 2.8mm or 4.3mm or 5.7mm wide

files are smooth on three sides with teeth on the 2.8mm wide edge

this is called warding and allows the file to rub along the sides of the

without widening it.

or a budget option

40 grit diamond flat file suitable for nut seating

5.5mm by 1.5mm profile

abrasive length L1 50mm

overall length 140mm