Four -stroke engine ,more powerful. Product name:Knapsack Brush cutter(ST-BC139)Product model:ST-BC139Engine type:Air-cooled,four-stroke,single cylinger gasolineEngine power:0.9kw/6500 r/minEngine Displacement:31ccCarburetor:Diaphragm typeIding speed:2600-2800r/minFuel tank capacity:1.0LPipe diameter:26mmN.W/G.W:7.7kg/8.8kgPacking size:33x33x45cm(Engine carton) 165x11x814cm(shaft carton)