The futaba to JR cords are uni-directional. They only allow information to be passed one way. By using this cord the JR must be the master and the futaba must be the slave. This would be fine if you go JR or Spektrum. In other words, if you decide to go with JR (or Spektrum) and your instructor only has Futaba as a buddy box, then buy the JR to futaba cord. Use your JR or Spektrum radio as the master, and his futaba as the slave. However, if you go with Futaba in your plane, and your instructor only has JR equipment, then you will be out of luck, as the cord doesn't work in reverse. But, you can generally get a compatible buddy box for around 50 bucks if you had to. I think it boils down to personal preference.

At least, that is how the cord worked when it was first introduced. There may be something new out there that I'm unaware of. If so, I'm SURE someone will jump all over me, yelling about how WRONG I am.