The Atoma Diamond Top Replacement #140 Sharpening Stone have their own custom product that is made of 100% polyester and is a custom fit for their body. They also have official brand licensed product that are made of 100% cotton and are a standard fit.
Atoma
Specifications:
Knife Type: Sharpening Stone
Steel Type: Diamond ()
Blade Hardness: HRC
Blade Length: 209mm (8.2″)
Blade Height: 75mm (3″)
Blade Thickness: 1mm (0″)
Weight: 134g (4.7 ounces)