EASY TO USE: These bits are specially designed for Electric Chainsaw Sharpener. Only 2 steps to replace. By the way, this titanium-plated files have harder nature, which reduces the number of times you have to replace it. FAST RESULT: Because there are full and evenly distributed particles on the chainsaw bits, these files can sharpen the chain saw chain steadily and efficiently. Only a few minutes, troublesome hand sharpening once and for all. Note: There may be many black spots on the wheel . It's not that the titanium coating has fallen off, but that the titanium and silicon carbide mixed. This is better for using. : The latest, hardest titanium-plated Diamond Wheels we'e ever made, adopted titanium plating process, which means you will enjoy 20% longer of these bits than others non-titanium-plated. SUITABLE: 3/16 inch wheels for 0.325 inch chain, big 3/8 chainsaw chain., Manufacturer: Bordhap