Foredom Diamond Hone Plastic Handle, 400 Grit, Super Fine, Blue
Hand file and shape anything from glass, metal, stone, bone and plastic, and for sharpening steel instruments.
Sharpen or reshape abrasive points by lightly rotating the point against the diamond surface.
Size: 150 x 19 x 4mm. (6” L) Sanding area 51 x 19mm (3/4” wide x 2”)
Also available in other grits here - 250, 600, 1200.