Features: No external power requires. With useful functions: electricity delay, output test, etc. The LCD can show the data for easy reading. Specification: Model: JVR 800-2 Monitoring Circuit: L1, L2, L3 Overvoltage setting range: 200-600V Undervoltage setting range: 150-500V Delay time for overvoltage and undervoltage: 0.1-30s Delay time for phase loss: 0.1-30s Delay time for phase sequence: 0.1-30s Start delay time: 0-999s Auto reset mode: ON/OFF Auto reset time: 0.1-999s Timer and counter input: AC/DC 80-450V Output contacts: 1 C/O,1NC Contact capacity: 6A ,250VAC Dimensions (H*W*D): 80*43*54mm/3.15*1.69*2.12inch Mounting: suitable for 35mm rail Weight: 129g . Note: Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.