They will work once you get the hang of them.
Your best bet is the Oregon or STIHL sharpening kit. It looks like a flat plate about 1 1/4" inches wide and about 7" long. The file fits in a groove in the plate so it hold the right size file with 1/5 of it sticking above the cutter tooth.
It is the one seen in this video.
STIHL Incorporated USA -- Information -- Manufacturing the World's Number One Selling Brand of Chain Saws