CyberPower’s CP900AVR has a fairly easy-to-use interface with just two buttons (electrical power on/off and mute) and 4 indicator lights (showing if the device is turned on, when the battery backup kicks in, when AVR is activated, and when there’s a power overload) about the entrance of your device. Photo: https://prefabricatedstructure61481.collectblogs.com/81030388/the-2-minute-rule-for-ups-battery-lithium