This is the Hitec HS-877MG High Response Low Profile Digital Servo.
FEATURES: Coreless motor
Ideal for electric vehicles, 1/10 scale glow powered vehicles, .30 -
.90 size glow powered helis and 600 and larger class electric
Metal gears with dual ball bearings
Water and dust resistant
INCLUDES: Hitec HS-877MG Servo with 1.7" (44mm) Double Arm, 0.98" (25mm) Single
Arm, 3mm Horn Screw, four each Grommets, Eyelets, and Screws
SPECS: 4.8V 6.0V
Speed: 0.12 sec/60° 0.10 sec/60°
Torque: 99.89 oz/in 124.98 oz/in
Weight: 1.6oz (45.0g)
Dimensions: 1.59 x 0.82 x 1.0" (40.4 x 21 x 25.4mm)
COMMENTS: A note on Coreless motors. A conventional servo motor has a steel
core armature wrapped with with wire that spins inside the magnets.
In a Coreless design, the armature uses a thin wire mesh that forms
a cup that spins around the outside of the magnet eliminating the
heavy steel core. This design is much lighter resulting in smoother
operation and faster response time.