Hello there it's 20"3/8 058 1.5mm for 200 series Husqvarna yeah some modifications so it oils I just use a round file and extend the hole up words until I break through into rails and customise it from there take no time at with a round file and the archer bars are really good I've used the snot out of mine and it's holding up real good.

What Archer bar are you running on the 850 any modification required to get it to fit and oil?