Von Ruden 110-382 G 1:2 Ratio Right Angle Double Shaft Gear Box Speed ReducerRatio: 1: 2 Input RPM: 1750 Output RPM: 3500 Input shaft diameter: 1 1 2" Output shaft diameter: 1 1 4" Vent included Approximate dimensions of main body not including bell shaped motor adaptor (If Included) Length: 8" Width: 9" Height: 8" All gear reducers must have a breather vent. This allows for expansion and contraction of the air within the casing as a result of temperature changes. If a gearbox is used without a breather, oil leakage and seal