Freehand filing drifts. The File-N-Joint clamps to the guide bar and holds the file where it should be, so every tooth comes out the same. Elof Granberg invented it more than 60 years ago and it's still the standard for accurate field sharpening.

Calibrated swivel markings set the sharpening angle, and integrated guides set file height and tooth length. It sharpens all major chain pitches and lowers depth gauges too. Cast aluminium and zinc-plated steel, made in the USA. Takes standard 8in round and flat files, sold separately.