Ailunce AY04 is the High Gain Yagi 144&430 MHz Directional Antenna, and you can refer to the video below to install it.
After completing installing the antenna and if we have the test instrument, we need to check if the frequency is tuning OK via checking the SWR. Under normal circumstances, the SWR on144/430 band is the lowest, and less than 1.5. we can adjust the two matching pieces shown in the picture as below.
If the SWR in the VHF band is on the high side, please adjust the matching pieces of VHF outward. Same for UHF.