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 01W Transmitters: Distance 01-1MFor 2W/5W Transmitters: 1-For 10W Transmitters: 2-5MFor 50W Transmitters: About 3-10MHow 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-held walkie-talkie about one meter from the field strength meter, do not get too closeSo as not to burn the field strength meter due to strong signals. And press PTT button in your radio to make it enter into transmitting state. At the moment, the pointer of the field strength meter should indicate the signal. The stronger the signal, the bigger the indication.- Amplitude Adjustment: If the pointer of the field strength meter exceeds the maximum range, you can adjust it to let the pointer point to an appropriate position.size:115 x 90 x 70MMMaterial:ABScolour:whitePackage Contents:1 x Field Strength MeterOnly 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.