... efficient 3.Positional accuracy is hig. Ultrasonic Drilling and Carving Machine Voltage:220VPower:2.5KWWorking frequency:15kHz-20kHzSize:540mm*500mm ... overload, overcurrent, overvoltage, automatic protection 3, large power, efficient and save energy, no radiation, no pollution 5, suitable for processing ... jades, crystals, agates, glasses, hard alloys and all kinds of semi-precious stones ...