QWinOut Z16 CNC Aluminum Folding Arm Tube Joint DIY for Dia 16mm Automatic Auto RC Quadcopter Hexacopter Multirotor Video Reference: http://v.youku.com/v_show/id_XODMyMTQzODYw.html To Increase Flying Stability, a 5 Degree Up-Tilt Angle Is Applied. CNC Aluminum, Suit For d16mm/d25mm Tube Arms. This Item Suit for Auto Edition RC Quadcopter Hexacopter Multicopter With 8pcs of M2.5*8 Screws for Center Plate