This pack includes two genuine Rotatech chainsaw chains designed for STIHL MS170 and MS170E chainsaws with a 12-inch bar. Ensure you check the specifications of your current chain to confirm compatibility, particularly by counting the drive links on the inside of the chain. These premium quality chains are engineered to stay sharp for longer. It is recommended to replace your guide bar for every three chains used; compatible guide bars are also available separately. Rotatech offers a range of related products including chain oil, guide bars, files, and sprockets, catering to professionals such as arborists, forestry workers, farmers, and wood processors, as well as home users.