This is a very unique and aggressive no-nonsense sharpening puck that is made from what would normally be waste material from other pucks. It is a mix of aluminum oxide, silicon carbide, and a small amount of diamond in mixed grits. This varied blend of grits and materials give this puck the ability to very rapidly remove metal stock while leaving a much more polished finish than one would expect. It's ability to rapidly remove material lends itself very well to repairing big chips and dings in the field or where access to grinders is limited. This puck is nice and light and close to half the size of our Arctic Fox sharpening puck. Although it's not necessary we do recommend saturating the puck with water before use. GRIT - Medium/Coarse.