1.Variable ratio electric engine gearbox 2.Body material,aluminium alloy and cast iron 3.Convenient mounting for gears,motors ... Features, 1) High precision of speed regulating for electric engine ... ,assorted as UDL0.18,UDL0.37,UDL0.55,UDL0.75,aluminium alloy body; UD1.1,UD1.5,UD2.2,UD3.0,UD4 ...