Features: Working principle:when main power close, it can automatic transfer to generator (generator should on),when main power is restored,it will transfer to main power. The changeover Switches is make of flame retardant plastic materials, with excellent insulation, highly temperature resistance. Double power automatic transfer Switches can be operated automatically or manually, the millisecond switching is uninterrupted, the installation and maintenance is convenient. This automatic transfer Switches is used in various occasion where continuous power outages is not allowed, such as homes, shopping mall, factories, laboratories, farm. When the normal power supply is abnormal, the backups power supply works immediately to ensure the continuities, reliability and safety of the power supply. Specifications: Materials: Plastic Working current: 100A Working voltage: 400VAC Insulation voltage: 690VAC Impacts resistant voltage: 8kV Size: about 143x96mm/5.63x3.78inch Note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1pc Automatic Transfer Switches