This is the Hitec HS-82MG Metal Gear Micro Universal Servo.  Because this servo has the universal connector, it will work with JR, Hitec, Futaba, and Airtronics Z radio systems.  These are great for small planes, gliders, electric helicopters and 1/18 scale cars.

Hitec took one of their top selling servos and made it even better. Based on the ultra popular HS-81MG, the HS-82MG gets a new stronger motor and updated electronics for more precise centering. The HS-82MG is perfect for smaller aircraft and helicopters where a durable geartrain is required.

Features: For small planes, gliders, electric helicopters and 1/18 scale cars

Includes:
HS-82MG Metal Gear Micro Servo with universal connector and mounting hardware
One 0.67" (17mm) diameter horn
One 1.1" (29mm) double arm
One 0.90" (23mm) 4-point horn

Specifications:
Speed: 0.12 sec/60° at 4.8V
0.10 sec/60° at 6.0V
Torque: 38.88oz-in (2.8kg-cm) at 4.8V
47.22oz-in (3.4kg-cm) at 6.0V
Weight: 0.66oz (19.0g)
Size: 1.17 x 0.47 x 1.16" (29.8 x 12.0 x 29.6mm)