STIHL Genuine Universal Oil Seal Puller (works on all saws) 5910 890 4400

A must have for any serious Chainsaw and Small Engine Mechanic. It allows you to change any crankcase seals without the need to split the crankcases thereby saving a lot of time.
It is not a cheap tool, but it is German made and very high end quality being good steel, it will stand up to years of constant use and will serve you well