Adjusting RF frequency can give better cutting finish on certain materials such as acrylics, PetG, etc, every material has its own absobsion frequencies, get the frequency right for that material and it custs and engraves better, DC tubes are Fixed, you can adjust the values in the controller vendor settings, but it does not affect the frequency of Glass co2 tubes as they are usualy fixed at 20khz, turning the RF frequency up or down tunes it to the material, It is noticable on ebgraved items on the Odin, ist almost spotless, far less smoke generated than on the CO2 versions. Beam diameter is smaller and mode is better, you can run RF at full power all day,