S8912 SHV2K with big block top case and bigger gears.
Reinforced and redesigned top case and gears to make the servo more durable ever.  New design helps prevent wiggling pins inside the top case which would create gear gap during flight and would be a cause to damage the gears.
 
■programmable
 Nutral, endpoint,gain etc(Works with PWM XBUS)120°150°180°(Works with PWM   XBUS)Synchronize(Works with PWM XBUS)
■Super steel full metal gear(Gear B brass)
■wide voltage
■BIG upper ball bearing (12x6) bottom(10x6)
■Special design Brushless motor
 
S8912 SHV with 2K firmware gives you more locked in feeling. Enjoy! 12V servo benefits Using low amperage and less stress:1) Extends servo life2) Extends battery usage time3) Ability to keep steady torque while flying4) Industrial friendly
 
Operation voltage: 12.6V Torque: 972.1 oz-in 70 kg-cm
Speed: 0.11 sec/60 deg
Weight: 2.79 oz / 79g
Dimension: 1.57 x 0.79 x 1.59 in / 40 x 20 x 45 mm 
 
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.