Brand Name: GTB Origin: CN Tool Supplies: Cutting Material: Aluminum Upgrade Parts/Accessories: 550/600 Trex Rotor Head RC Parts & Accs: 550/600 Trex Rotor Head Use: 550/600 Trex Rotor Head Remote Control Peripherals/Devices: 550/600 Trex Rotor Head For Vehicle Type: 550/600 Trex Rotor Head Four-wheel Drive Attributes: 550/600 Trex Rotor Head Trex 550 600 DFC 4 Blades Rotor Head Kit for Align Trex 600 550 Helicopter Upgrade PartsMain Shaft Diameter:10mmFit thickness 12mm Blade(The shaft please install by customer other assembled)