Man, chainsaws are so much more complicated than I thought. I bought a Stihl 310 a while back. I have no clue what bar, chain, or sprockets were on it. I recently replaced the clutch sprocket with this: https://www.amazon.com/gp/product/B015OCO8JC/ref=ppx_yo_dt_b_asin_title_o08__o00_s00?ie=UTF8&psc=1 To me, that tells me, no matter what I had before, I just made my saw a 3/8" pitch. I also bought this: https://www.amazon.com/gp/product/B00HY96EW8/ref=oh_aui_search_asin_title?ie=UTF8&psc=1 I am now thinking that I bought a sharpener that is incompatible with the chains that my new clutch sprocket will demand (3/8" pitch). 1. Is that right? Further, I have a smaller Stihl (can't remember the model). I don't know what pitch it is, but I'll look at the bar. 2. Does that mean I may need to buy a 3/8" sharpener for my 310 and its chain and then, if my smaller one is .325 pitch... I'll need a second sharpener? --- Also, I guess if my 310 was originally .325, that means all my old chains will not fit the new 3/8 clutch sprocket I put on? So, I throw them in the garbage? Dang I'm confused.