GARTT DIY GT500 FBL TT 2.4GHz 6Ch Flybaless Torque Tube RC Helicopter fits Align Trex 500 helicopter KIT Version Fits Align Trex 500 perfectly offers an excellent power-to-weight ratio that makes for stellar 3D performance high quality tail bearings and tight tolerances to ensure no slop in the tail assembly and locked-in tail performance for the most extreme of 3D flying. 90% pre-assembled Excellent power-to-weight ratio