A5840 bug gearbox reducerthe pinon equipment inner gap size : 2.0mm 2.3mm.Ratio: 17 to1,31 to1, 50to1, 100to1, 200to1, 290to 1, 505 to1,670to 1, , --- this gear field can event with 31ZY 555 545 42BY stepper motor 3650 brsushless dc motor if you want to match different dc motor , pls touch us , and confirm pionin gear inner gap sizeReducer picture :Worm equipment reducergearbox reducer drawing :gearbox case for reduction motorplanetary reducer applicationthe gearbox reucer can math with excessive torque electrical dc motor 555, 550,545, 36zy.3650 and many others dc motormotor cataloguespur equipment ,ptpr . n20 motor , brushless motor and motor motive force , stepper motor and many others in factory shop .Contact information:email : cathy88085@qq.comwechat : 13265820577whatsAPP:: 13265820577