The RocHobby Critical Mass does not only look fantastic but it is a true joy to fly. We think you will enjoy the split flaps, servoless electric retracts, and great all around flight characteristics. The Critical Mass is capable of aerobatics that would leave lesser planes in the dust. This plane is made from EPO foam for maximum strength and durability. Speaking of durability, the split flaps have nylon hinges and the retracts have metal trunnions.