Ryobi RY08420 42cc Gas Powered 2-Cycle Backpack Leaf Blower 185 mph 50:1 Gas to Oil ratio, which is 2.6oz of oil to 1 gallon of gas. Do NOT use E85 gas Contoured Back/Shoulder Harness and Adjustable fit for Less User Fatigue Unique Engine Position for Maximized Air Flow Large 42cc Engine for Optimal Clearing Power Special Downward Angle Design for User Comfort