Du-Bro Long Dual Servo Arms (For Hitec, Tower, Hobbico, Command) Part No: 3342. A servo arm design for large aircraft. This dual arm allows for straight and in-line movement of the control surface. Made of long fiber composites, this arm is super strong and will provide the maximum security. The Long Dual Servo Arms include heavy duty ball links for 4-40 pushrods and assembly hardware. The arms have 3 mounting holes for increased or decreased servo throw. Dimension from center to the end mounting hole: 1.343" (34.13 mm)