Is this easy file suitable for the following chain? 12" Picco Micro (PM3) 1/4"P 1.1mm (.043") 64 Links Chain Loop fits Stihl MS15OT & MSA16OT Chainsaws - OEM No. 3670 000 0064

No, that one would not be suitable as it's for a 3/8p chain, you would need the following: https://www.lsengineers.co.uk/2-in-1-easyfile-1-4-p-3-2mm-genuine-stihl-oem-no-5605-750-4306.html