A surface for sharpening generic blades.

There are various versions of this tool. Some lay on the table and others are handheld. Some are mechanically propelled and others not. The one pictured here is a simple handheld block.

To use, make the stone wet, then hold firmly in one hand, facing towards the floor at a comfortable angle. Place the blade at the end nearest to your hand, facing upward, and push the blade away from you with a bit of pressure and speed. Repeat as many times as necessary to achieve a suitable sharpness, and make sure to alternate between sides of the blade, to ensure the blade's sharp point remains in the middle.