I'll check into this...available from the Stihl dealer??
I do not know. It is mentioned in the owner's manual, but no part # is given. So you might want to find it in your manual and bring that to the dealer...
It's on page 37 of this pdf: http://www.stihlusa.com/stihl_ownersmanuals/MS34136_Manual.pdf
corresponding to page 36 of the printed manual.