This is a fantastic tool! I didn't expect it be much of an improvement over simple flat filing, but it really is. It always you precisely control the pressure on the file with no bending of the file. I've been tuning for over 35 years, concave skis have always been a challenge. Using this tool I was able to produce a TOTALLY flat ski in about 25 minutes. Being able to do this myself at home is fantastic. I live near major ski resorts in CO, but its still a frustrating endeavor to find a shop that can consistently grind a railed ski flat. I wish I would have bought one of these 30 years ago! I chose the macro cut file and recommend that choice, its much quicker than my 1st cut files.