usmile F450 Quadcopter Frame Kit with Integrated PCB Wiring Ultra-high strength materials: PA66 + 30 GF arm Integrated PCB circuit board, save you lots of assembling time Large installation space: optimized design, lots of space to install different flight control systems and accessories. Colorful arm make your flight more dazzling and fun Suited for beginners or senior pilots, similar with F550 S500 frame