1. AC/DC 2.40% duty cycle, 3. MMA 4. reasonable price ... power correction, MOSFET, AC/DC , soft switch, inverter with 100 kHz high frequency;2.Compact structure, stable welding current, steady and intensive arc ... control performance, MMA 4.Thermostatic protection, over-voltage protection, over-current protection, under-voltage protection, pedal control interface for safe operation ...