These double-sided credit card-sized diamond sharpening stones are perfect to slip in the pocket of your smock so you have a sharpening tool at your immediate disposal.
The 300/600 is possibly the most useful of the credit card range. While the 300 grit side is great for putting an edge on a variety of tools very quickly, the 600 grit allows you to really refine the edge. The card comes in a protective, plastic wallet to keep it as pristine as possible.
You are purchasing:
1 x 300/600 grit Credit Card sized Monocrystalline Diamond Stone
James Barry developed his diamond whetstones to be of the highest quality. They are monocrystalline - which are far superior to their cheaper, polycrstalline counterparts; and they are electroplated to their nickel carbon steel base 'card' (which is produced to be as flat as possible) instead of being impregnated/glued on.
Both of these considerations give these diamond credit cards an enormous longevity advangate over cheaper alternatives. If you look after your stone it should last you a lifetime.
These diamond whetstones come with a 5 year guarantee as standard as long as they are used with lapping fluid to lubricate the chisels being sharpened, and not oil or water.