This is the Hitec HS-646WP High Voltage Waterproof Ultra Torque Servo.

FEATURES: Waterproof-industry first IP67 rating, ranking these as among the  
most durable and reliable servos for wet conditions Ideal for boats, 1/8 and 1/10 scale cars.                          
7.4V 2-cell LiPo and 6-cell NiMH compatible              
3-pole motor                                                       
Dual ball bearings                                                 

INCLUDES: Hitec HS-646WP Servo with 1.02" (26mm) Single Arm, 2.3" (59mm) Double
Arm, 1.6" (42mm) Four Point Horn, 0.98" (25mm) Single Arm and    
Mounting Hardware                                                

SPECS:              6.0V               7.4V                                
Speed:  0.20 sec at 60°    0.17 sec at 60°                       
Torque: 133oz/in (9.6kg/cm) 161 oz/in (11.6kg/cm)                 
Size: 1.65 x 0.83 x 1.57" (41.8 x 21.0 x 40.0mm)