Pferd first came out with the 2 in 1 file guides several years ago, and I scooped one up. Pretty sure they manufacture the Stihl branded version as well. I'll never go back to using a standard round file/guide and flat file again! There's something to be said for filing consistency, especially if you bore cut trees like I do. Nothing worse than an inconsistent full chisel chain and frozen wood!
No grinders or dremels for this guy, just the 2 in 1. I cut Ash all Winter at work, and have thoroughly enjoyed using a 362CM with a 20" for felling, and a 261 with an 18" for limbing and bucking the last few years.
-Nick