The ABB PowerValue 11 RT G2 1kVA External Battery Module is an additional item for the PowerValue 11 RT G2 1 kVA UPS to extend its runtime. 

PowerValue External Battery Modules (EBM) allow you to extend the runtime of ABB PowerValue UPS systems. Up to 4 EBMs can be attached to a UPS and the chart below demonstrates the extended runtime in minutes depending on the load being supplied.