Frontier L series 12KVA/ 15KVA/ 20KVA Features: 1 True Sinewave Double Conversion On-line UPS 2 Microprocessor Control Guarantees High Reliability 3 Extended Back-up Time with External Battery Bank Adopt the Most Advanced IGBT Devices RS-232 Communication Port Smart UPS Monitoring Interface Auto Restart and Cold Start Function Intelligent Short Circuit Protection User-friendly LCD& LED Display Low Frequency Design