HFX Air Model 2 Transmitter, built for Plantraco 900Mhz Airplane Receivers. Tx has negative Expo, V-Tail, and Normal mixing modes. Full Proportional 4 Channel Output. 6 user-selectable frequencies. Built-In Precision Lithium Polymer Charger for Bahoma LP90 Cell. FMS flight sim input jack is ready for the FMS flight sim cable available separately. Built-in Buddy Box RJ-12 jack turns your old 72Mhz Hitec or Futaba into 900Mhz - Bonus Feature! What a cool RC Plane controller!