Wltoys V912 2.4ghz Radio System with Large Single Blade RC Helicopter included 4CH Transmitter Model 2 2.4ghz Radio System;Mode 2 Transmitter Setup. Large rotor diameter is inherently more stable. Li-Po powered for increased power and flight time. Transmitter can be used for V911, V929, V939, V949. Extra Tail Blade and Main Blades.