Wide frequency band and high sensitivity 100K-1GHz. (The antenna is 400-470Mz. To test different frequency signals and better effect and sensitivity, please use antennas with different frequency). To protect its current meter, the amplitude of pointer is adjustable. Built-in automatic damping function prevents the hands from swinging too fast to cause damage. Compact size for easy carrying. Simple and beautiful design. Testing Sensitivity: For 0.1W Transmitters: Distance 0.1-1M For 2W/5W Transmitters: 1- For 10W Transmitters: 2-5M For 50W Transmitters: About 3-10M How to Use It? Before using, please adjust the amplitude to the far left side. The length of your antenna depends on testing frequency. 1/4 wavelength is recommended. Keep your hand- walkie-talkie about one meter from strength meter, do not get too close So as not to burn strength meter due to strong signals. And press PTT button in your radio to enter into transmitting state. At the moment, the pointer of strength meter should indicate the signal. The stronger the signal, the bigger the indication. - Amplitude Adjustment: If the pointer of strength meter exceeds the maximum range, you can adjust it to let the pointer point to an appropriate position. size:115 x 90 x 70MM Material:ABS colour:white Package Contents: 1 x Field Strength Meter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.