S8911BL 2K 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.
 
 
[Stall Torque]   
 51.7kgs  (6.6V) / 58.0kgs  (7.4V) / 65.8kgs (8.4V)kg・cm
 718.4oz (6.6V) / 805.4oz (7.4V) / 914.3oz (8.4V)oz・in
[Speed]
0.15 (6.6V)/0.13 (7.4V)/0.11 (8.4V) Sec/60°
[Weight]
85.5 g / 3.02 in
[diemension]
35 x 20 x 41.5 mm / 1.38 x 0.79x 1.634 in
[Length of lead harness]
300mm
[Operating Voltage]
4.5V - 8.5V
■programmable
 Neutral, 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 valtage
■BIG upperl ball bearing (12x6) bottom(10x6)
■Special desigen Brushress motor