I always upgrade mine partly for this reason. The other reason is that the newer 10mm "s" one will be available LONG after the other one is obsolete and NLA. I am sort of surprised that it is still available today. Saws haven't used this for about 2 decades now. The difference is Old = 8mm hole vs. New = 10mm hole. I usually use a 15/32" drill. I would rather it be a little tight than a little loose.