Product Overview The STW-4000C is a multi-functional 4-in-1 UPS modified sine wave power inverter that combines battery charging, inversion, and uninterruptible power transfer in one compact unit. It converts 12V DC battery energy into 220V AC output. When grid power cuts off, it switches over instantly to supply power to your home appliances — an ideal solution for regions with unstable electricity supply. Key Features Modified sine wave output — reliable and cost-effective