It is coming with 2K firmware.  You will have more locked in feeling.  
Same as JR PROPO "NX3421" is for general use of RC air planes
 
[Torque]  5.9 (6.6V) / 6.6 (7.4V)) / 7.5 (8.4V) kg･cm
                  81.7 (6.6V) / 91.7 (7.4V)) / 104.0 (8.4V) 0z･in
[Speed] 0.18 (6.0V)/0.16 (7.4V))/0.14 (8.4V) Sec/60°
[diemension] 26.5mm x 15.0mm x 33mm
[Length of lead harness] 300mm
[Operating Voltage] 4.5V - 8.5V
 
DFA is pleased to announce the release of our new XBus programmable servos, allowing not only serial servo connection, but also individual servo programming with servo adjustments to suit every application.
Highlights : This servos automatically detect the type of output they are plugged into - conventional receiver PWM outputs, or XBus. This means Programmble servos are XBus compatible, and also compatible with PWM receiver signals without any converter, allowing modelers to use conventional receiver systems. * Compatible receiver systems : DMSS · DSMJ · 72MHz · 40MHz When used on a DFA JR XBus system, the Programamble servos can be programmed in ways not previously possible. No additional programming device is necessary these servos can be setup using a DFA 8+6 DFA T44 ,JR XG series transmitter. Changes made to servo programming are immediately apparent. Not only can servo direction and travel be adjusted, but it is now possible to fine tune servo gain, dead band and boost to suit your aircraft and desired response. This precise setup allows servo hunting to be eliminated and precise feel maintained. *Wide Voltage * Double ball bearings * Slow start function *Compatible with any radio using PWM control *XBus compatible allowing *120 to 180 deg travel * featureYou can adjust Dumping,Hold,Deadband...etc * Do not use this servo under the different voltage other than specified * If used on a large and Heavy control surface *Try to adjust Dumping.Hold .Dead band.Boost etc... You will set it up perfect condition.(use RX Xbus port and Xbus TX)
 
The firmware in a 2k servo verifies the position of the servo arm two thousand times each second, 
while the firmware found in previous servos verify the arm's position one thousand times per second.
This greater number of verifications makes for a very precise servo, and gives it a more "solid" feel.
It is recommended to use a booster cable with 2k servos to ensure steady voltage at all times.
■programmable Neutral, endpoint,gain etc(Works with PWM XBUS)120°150°180°(Works with PWM XBUS)
■ Metal gear(Gear B Plastic)
■ wide valtage
■ Double ball bearings
■ Coreless motor
■ SYNC