This servo is a great servo for your sized helicopters or any other applications where high speed, precision and strength are needed. 
Fit for 550-700 helicopter cyclic.

Servo: Digital
Gear: Metal
Voltage Rating: 6.0V to 8.4V 
Motor: Coreless

Torque:
5.5Kg. cm @ 6.0V
6.5Kg. cm @ 7.4V
7.5Kg. cm @ 8.4V

Speed:
.05 sec/60* @ 6.0V
.045 sec/60* @ 7.4V
.04 sec/60* @ 8.4V

Dimensions: 40.5*20*37mm
Weight: 70g