These 350-type rc helicopters come fully assembled with all pre-flight adjustments completed. Using the latest technology available, the receiver, gyro, servo and motor control amp are combined into the high performance one-piece Flight Control Unit, and transmitter is with mode-lock switch. Modified PIT and PLT parameter is lockable. It is READY TO FLY with 10-15 minutes of flight time on each charge, only requires AA Batteries for Transmitter. Optional Li- poly battery (included with selected helis) will help to achieve better performance and longer flight time.