Two Bearings: less friction and slop. Because of the many vibrations and mechanical loads placed on the servo in RC helicopters, non bearing servos do develop slop very quickly and of course this makes control more sluggish and vague feeling.
Metal Gears: a popular choice for the obvious great strength and won't strip easily, survived many crashes that wrecked plastic servos.
Water Resistant: worked perfectly in the snow, rain, water and mud, making great sense with nitro RC helicopters or any nitro model that exposes the servo to nitro goo.
Wire Connecting: standard 3-pole wire, the brown for "ground", the red for "power supply", the orange for "PWM control".
Faster control response, constant torque throughout the servo travel. Equipped square jamproof potentiometer.