The Thiers Issard 0.25 Micron (Silver) Diamond Sharpening Paste is a extra-fine-grit sharpening compound which will put a smooth and refined edge on a straight razor. When used in combination with the 1 Micron (Red) Paste and Chromox Paste, it will maintain a regularly used razor. All the diamond particles used in Thiers Issard Sharpening Pastes are very carefully sorted to make sure that particles in each mix are exactly the given grade size. This is important when producing a highly refined razor edge. Carrier paste is water-based and non-toxic if accidentally ingested.