... saving tech 4.service life up to 10years JWF ROOF BIRDHOUSE VENTILATOR 300/4001, smooth operation and long ... service life up to 10 yearsJWF range poultry house roof fan parametersModelSize (mm)Voltage (V)Frequency (Hz)Input ... lubrication (grease).6, in case of winter snow, freezing date, must always be switched on to ... prevent snow blower outlet plug.7, after a long ...