I stopped by the dealership for oil and picked up two packs of files for sharpening the chains on my saws when necessary.I got 3/16 and 7/32 for my 260 pro and 362.The 260 has a .325 and the 362 has 3/8.
Had to check cause these numbers get's me confused. Stihl recommends 13/64 for their 3/8" chain but lots of people around here use the 7/32" files, me included. Some use the 13/64 then switch to the 7/32 when the chain gets used up some. Anyways, you should be allright.
Since I have a variety of saws and they almost all have different size chains I stock some of every size file and just use what seems to fit. A chain will use a different size file as it wears (I use a larger diameter file on worn chains). I use semi-chisel chains and always free hand sharpen them with good results. Some people just cannot hand sharpen a chain with acceptable results and maybe need to have them sharpened or get a grinder. I have found grinders go through chains in a hurry since they make all the teeth even. This is nice but not necessary in my opinion. All the teeth need to be sharp but not all the same length. (others may not agree and sharpen away...) It works for me. Files are about a buck apiece if you buy them by the dozen so having a dozen of five different sizes isn't going to break the bank.
3/16 file for .325 chain
5/32 file for 3/8 low profile chain
7/32 file for 3/8 chain
I use .325 chain, so I know for sure about the 3/16 file, the 3/8 info is according to Bailey's.
Hope that helped you.