Features: Quality material with good impact-resistance and can withstand the impact of hard landing. Strong anti-fall ability, can achieve hovering, cruising, even rolling and other flight requires. Adopt optimized-design, integrated PCB circuit board, providing adequate installation space for flight control system and accessories. Two-color force arm used to distinguish the direction so that you fly in the right direction, making your flight more fun and obvious to find. Equipped with mounting screws,you can assemble it by youself quickly and easily. Specifications: Material: Metal Size: about 20cm/7.87inch(single arm length) Color: Black White, Black Red(optional) Applicable Models: Suitable for F330 / F450 / F550 Quadcopters Package Includes: 1Pc Upper Plate 1Pc Lower Plate 4Pcs Force Arm 25Pcs M2.5x6 Rack Screws 16Pcs M3x8 Motor Screws note: Please allow 0-1cm error due to manual measurement. Please allow for slight color difference due to different monitor resolution.