Sig Somethin Extra .40 size. They are unbeliavably forgiving and slow down to where you can walk out and catch it if you want to. My son handed me back the radio with wide open throttle (o.s. .60) straight down and I 180'd it in less than 5 feet. I have crashed it about 4 times, ripped the gear off a few times, and it is still flying strong. Turn down your throws and it is more gentle than any trainer, turn em up and go nuts. My friend built it from a kit and reported it being very simple to build. It is also a great platform to begin learning 3d stuff/aero. Good luck.