Scrench Chain Saw Maintenance & Repair Tool. A combination screwdriver and wrench in one handy tool. It is used to remove bar mount nuts for replacing the guide bar or chain and to adjust chain tension. It is compatible with some of the most popular model chainsaw brands such as Poulan, Poulan Pro, Husqvarna, Stihl, Echo, Shindaiwa, Jonsered, and Partner.