The Naniwa Professional 400 grit stone is hardcore. It eats up steel so fast that it makes serious repairs & bevel-setting a dream. Naniwa Professional stones are harder than most, so they stay flat better and last much longer than cheaper options.

When to use this stone:

• Cuts steel quickly and no soaking is required, just splash and go.
• Sets a good flat foundation for any knife thinning you are doing and takes out deep stratches very quickly, priming your knife for finer stones.
• Works great for touch-ups on rugged outdoor knives.
• Due to its hardness, it is by far the longest-lasting low grit stone available and will need much less truing than other low grit stones.
  

That said, always flatten your stone with a after sharpening.

About Naniwa - Naniwa is the biggest and best sharpening stone manufacturer in Japan. Their stones are among some of the highest quality in the world, good for both professional and amateur. They make a wide range of grits and densities, so you can choose the perfect stone for your needs and budget.