This is the Spektrum RC S614 Waterproof Metal Gear Servo 23 Tooth spline.
Specifications:
Gear Material: Steel
Bearing: Dual
Bushing Or Bearing: Bearing
Gear Type: Metal
Application: Surface
Overload Protection: No
Product Weight: 2.2 oz (62g)
Spline Count: 23 - Tooth
Water-Resistant: Yes
Input Voltage: 6.0V
Product Height: 1.6" (41 mm)
Servo Type: Digital
Connector Type: Universal
Product Length: 1.8" (46 mm)
Programmable: No
Servo Size Category: Standard
Connector Wire Length: 10.4" (264 mm)
Product Width: 0.8" (20 mm)
Motor Type: Brushed
Servo Operating Voltage: 6.0V
Maximum Servo Torque: 201.4oz-in (14.5kg-cm) at 6.0V