This is the easy to learn filing system that makes your saw chains cut like magic. The secret lies in the ability to sharpen cutters and depth gauges to theperfect edge and height. For years, professional saw users have been baffled by one sharpening device after the next, each one more complicated than the last. This system is so simple that a novice can sharpen chain better than many seasoned professionals. With each stroke, Chain Sharp forces the round file up into the top plate of the tooth, instead of down into the gullet, while the flat file shaves the depth gauge down to the perfect height. Proper angle is displayed at users thumb. You'll make old chains cut like new with this easy to use,and fully compatible filing system. Holds 3/16" file and 7/32" files for 3/8 and .404 pitch chain.