This is the HS-55 Sub Micro Servo from Hitec. This version of the servo has a universal connector which will fit Airtronics, JR, Hitec and Futaba receivers (be careful with the polarity of the connector for Futaba radios).

Specifications:
Speed: .17 sec/60 degrees @ 4.8V - .14 Sec/60 Degrees @ 6.0V
Torque: 15.27 oz-in @ 4.8V - 18.05 oz-in @ 6.0V
Weight: 0.28 oz
Length: .89" (22.8mm)
Width: 0.45" (11.6mm)
Height: 0.94" (24mm)