The Happymodel OVX300 VTX is based on the Open source project OpenVTX powered by JyeSmith from the EpxressLRS team. Open VTX aims to provide firmware with both the SmartAudio and Tramp protocols. Either protocol can be used on the flight controller and on VTx power up the protocol used is automatically detected by OpenVTx. Check out our other U.Fl VTXs, as well as the rest of our Happymodel selection! Specifications Input Voltage: 5V RF Output Power: 25-300mW Antenna Connector: U.Fl Power/Video Connection: Solder Pads Stack Size: Not Stack Mounted Dimensions: 15x14mm Weight: 0.9g Includes 1x Happymodel OVX300 25-300mW 5.8GHz U.Fl VTX w/ OpenVTX