These small sharpening stones are really unique. They feature a small 2 piece plastic protective case with a ring that allows you to attach it to your gear. Another unique feature is the the slot cut in one side of the case allowing you to sharpen pointy objects like your mine probes, grappling hook spikes, C-4 spikes and even fish hooks on the move without removing the stone from its case. The green plastic stone case and black oxide split ring may provide a clue about who they were made for.
A Note From The Legal Department: The sharp items shown are not included with Pocket Sharpening Stone. These Stones are brand new over-run from a government contractor friend. If we didn't say all this, someone would ask.