For those requiring a really heavy-duty servo arm, the Dubro "Super Strength" arms will fit the bill.

Details:

Black, fiber-reinforced composite plastic servo arms.

INCLUDES:

4 short, 2 long servo arms that extend in one direction from theservo center; one long arm that extends in two opposing directions fromthe servo center, and one 3-arm horn. Specs: Short: Mounting holes at: 7, 10 and 12mm. Total length-16mm Long: Mounting holes at: 8, 10, 13, 16, and 19mm Total length-22mm Dual: Mounting holes at: 6, 10, 12, 16, and 18mm Total length-22mm 3-arm: Mounting holes at: 7, 10, 13, 16, and 19mm Total length-22mm All measurements are from the center of the arm. The dual and 3-arm areonly from one side to center. Actual overall length for both: 44mm Fits the FUTABA servos with splined output shafts. BOX DIMENSIONS: 4.25" W. X .50" H. X 5.00" L. BOX WEIGHT: .03 LBS.