The HK Mi Series servos represent the next break through in high precision servo technology. Using Magnetic Induction, rather than a potentiometer, for an unsurpassed level of accuracy and performance.

A great servo for 550~600 Class helicopters such as the T-Rex 550 and HK600

Specs:
Voltage: 4.8v / 6v
Speed: 0.08sec / 60 deg (4.8v) - 0.07sec / 60 deg (6v) 
Torque: 9.7kg.cm (4.8v) - 11.8kg.com (6v)
Size: 40mm x 20mm x 39.2mm
Weight: 58g
Gear Train: Full Titanium Alloy
Motor: Coreless
 
Mi : Magnetic Induction, uses a Magnetic Rotary Encoder in place of a traditional potentiometer (invented in 1877). Magnetic Rotary encoders have a longer life and suffer less wear.