5/16 Dia is what my Poulan S25 with Sears' Label list in the specs. If you sharpen often or pay to have bad chains sharpened vs just touching them up, you need to try the Dremel type sharpener. A fellow impressed me in the woods with a Sears 12V off his truck in 1984. I purchased the 110V and have not used a file or had a chain sharpened since.

I have seen them at Northern tools, Home Depot,Sears and all look similar 12V, 110V or cordless (which I doubt will fit my budget for my need). LOL The link below is a You Tube Demo:

http://www.youtube.com/watch?v=muF5fHE3JAc

5/16 is huge. My other saw is an Stihl 041 Farmboss. It has a full size chain that I keep sharp with a 7/32 file and a mill file for the rakers. I can sharpen my Stihl in 15 minutes by hand. I like the fact that I can still do something with these clumsy mitts and near sighted eyes. I work by feel I find it more convenient than taking the chain to somebody. I like the sound of a file better than the buzz of the Dremel too.

I would suggest you go to the Oregon Chain selector guide and find the replacement chain for your saw. Once you've done that, you should be able to look at the specs and they'll tell you for sure if you need 5/32, 3/16, or 7/32 file. You'll need the saw model number to look it up.

Here is a link that might be useful: Oregon selector guide

You're OK with the 5/32 files. Your Sears chain number crosses to Oregon S52 Saw Chain, which is 3/8" pitch, 14" Long, 52 Links. Recommends 5/32 file.

OOPS, A Big Error!! 5/32 vs 5/16 Is The Spec I Should Have Typed. Easy Catch that I should have caught. The Dremel has worked good due to the excessive wear I get from cutting Pushed/Bulldozed wood vs standing wood. It allows many sharpening as files vs having it sharpened maybe 3 times and it's gone.

PS. Do You Have Many Backward Days? LOL!

Thanks guys. Loger, I was puzzled , then figured out it was a typo. The saw was my Dad's. I thought it was a POS, but it is a fine trimmer and easier to climb with than my Farm Boss.