... air should not contain enough dust and impurities to erode device. 1.6. Should not be subject from strong ... 10KHZ , 20KHZ, or 40KHZ, it’s up for you to choice.4.2. High terminal: 80KHZ, 200KHZ, or ... 300KHZ, it’s up for you to choice.5. Magnifier adjustment:There are six position for ... -- straight lineØ The base oval can be adjusted to normal size at high frequency when input voltage (13 ...