Whetstones for sharpening knives. 
The history of Wästilä Whetstone goes back for centuries and in its time whetstone provided employment and a source of income for the Längelmäki village. Wästilä Whetstone has also been imported to different parts of the world for both weapons and tools. 

Instructions: Wet your stone with water and grind parallel to the angle of the knife's edge.