New, unused whetstone, approximately 210mm, equivalent to a medium grit stone for knife sharpening (GC marking)

This is a whetstone with unknown specifications.
The outer box has the marking G C..

This is a new, unused item, but it has been stored.
There may be minor dirt due to storage.

Size: Approx. 210 x 55 x 27mm

Based on its general size and appearance, it is likely equivalent to a medium grit whetstone, but the specific grit is unknown.

*Since there are multiple items in stock, the posted photo is a representative image.
*Please refrain from price negotiations.