This has been covered many times in the chainsaw section. A lot of folks like the progressive kind where how far back the top plate has been filed back effects the actual distance if one would measure with a straight edge and feeler gauge. file o plate is another term you could search. Those often have two locations for soft or hard wood. I only use the kind with the depression in the middle, there is another with the depression at the end. I am no expert but think that .325 Stihl chain will not be fussy as to the kinds I have in mind. Vanguard or 1/4 inch pitch or bumper tie strap might be another matter.