Highlight : The selling light must be buy with the BMS together, it can not be used to old BMS, because the olde BMS light board port is 3.3V, now it is 12V.Please buy the accessary according to customer needs.If you only buy the accessary, we will not ship it because its cost can not cover the shpping costDaly Smart BMS Accessories Touch Control Screen LCD Display And CAN BUS AND LIGHT BOARDNOTICEplease confirm with customer service that if communication method compatible with certain bms . Pls refer to following link to understand how to use the touchable LCD Pls refer to following link to understand how to use bluetooth function Pls refer to following link to understand how to use PC function(UART/RS485/CAN communication) You can use the light board(battery capacity)to activate the bms, wake up the bms and show battery capacity.Daly Smart BMS Accessories Touch Control Screen LCD Display And CAN BUS AND LIGHT BOARDNOTICEplease confirm with customer service that if communication method compatible with certain bms . Pls refer to following link to understand how to use the touchable LCD Pls refer to following link to understand how to use bluetooth function Pls refer to following link to understand how to use PC function(UART/RS485/CAN communication) You can use the light board(battery capacity)to activate the bms, wake up the bms and show battery capacity.Daly Smart BMS Accessories Touch Control Screen LCD Display And CAN BUS AND LIGHT BOARDNOTICEplease confirm with customer service that if communication method compatible with certain bms . Pls refer to following link to understand how to use the touchable LCD Pls refer to following link to understand how to use bluetooth function Pls refer to following link to understand how to use PC function(UART/RS485/CAN communication)