OK, I am mad at myself. I was going to buy the new kit at Lee Valley and didn't do it before the sale ended. So I did an inventory to see what I really need since they are now selling them ala cart. This brought me to a question. What is the difference between 4xx slim and 6xx slim. Is it really just 2 inches? I looked in Paul Sellers book and he just recommends 3 files for an entire nest of saws. 7 Slim for 5 - 7 ppi, 7 X slim for 8 - 10 ppi and 6 XX slim for 11 on up. Does this mean that the xx slim is the same file in all lengths just longer or shorter? Do you need the 4" and 5" for the different size saws? As you may figure I am just getting into saw sharpening and was wondering what people think of Pauls suggestions. He seems to be fairly well regarded so I am just wondering. so Do you all use the suggestions from the distonian institute, The Lee Valley site that has the kit has slightly different suggestions that Distonian. Or can you get by with any file that has twice the space on the file to the tooth. Thanks, John