Spyderco Fine Grit Sharpening Stone with Sheath - 303F
SP303F: Fine Pocket Stone
Spyderco manufactures small rectangular pocket stones for portable field use and honing small items.
The 303F Fine Grit Pocket Stone fits in the palm and is packaged in a leather carrying case.
It is autoclave safe (ideal for dental tool sharpening) or can be cleaned with a plastic scouring pad and powdered abrasive cleanser.