The MPI 3" Aluminum Servo Arm features:

• Designed to fit Futaba
• Heavy duty Anodized Aluminum
• Clevis Connector hole is pre-drilled and tapped for 4/40 screw
• Extra security provided by an Allen head socket screw used to lock the arm onto your servo spline.

Uses:

• Arm size should be based on your linkage setup, the amount of throws you intend to have, and your flying style, however you can use these suggestions as a base:
• .40 size Nitro to 50cc can typically use 1" arms
• 50cc to 100cc can typically use 1.25" arms
• 100cc to 150cc can typically use 1.5" arms
• 150cc to 200cc can typically use 2" arms