This is the HS-7950TH High Speed, Ultra Torque Digital Servo from Hitec.

FEATURES: Ideal for giant scale planes, monster trucks and rock crawlers Coreless motor for precise centering and accuracy G2 programmable digital circuit, programmable features include; Dead Band Width Speed (reduction) Fail Safe Position Direction (CW/CCW) Fail Safe On/Off End Points Overload Protection Resolution High/Low Titanium gears that don't break or develop slop like conventional metal gears Capable of operating on two LiPo packs

INCLUDES: HS-7950TH High Speed, Ultra Torque Digital Servo with 1" (25.5mm) single arm horn, 1" (21.5mm) aluminum single arm horn, 0.85" (32mm) heavy duty single arm horn, 2.8" (72mm) heavy duty double arm horn, 2.3" (59mm) double arm horn, 1.8" (45mm) round horn, four eyelets, four rubber grommets, four 2x15mm mounting screws and instruction sheet

REQUIRES: Installing in model and connecting to control linkage and receiver

SPECS: Size: 1.57 x 0.79 x 1.50" (40 x 20 x 38mm) Weight: 2.40oz (68g) 6.0V 7.4V Speed: 0.15 sec 0.13 sec Torque: 403 oz/in 486 oz/in Drivetrain Type: Dual ball bearing

COMMENTS: This servo can be programmed with any Hitec digital servo programmer. However, the Overload Protection and Resolution High/ Low can only be programmed with the HFP-20, HPP-21 (HRCM4420) or the HPP-21+ (HRCM4421) A note on coreless motors-a conventional servo motor has a steel core armature wrapped with wire that spins inside the magnets. In a Coreless design, the armature uses a wire mesh that forms a cup that spins around the outside of the magnet. This arrangement is much lighter resulting in smoother operation and faster response time.  

BOX DIMENSIONS: 2.88" W. X 1.38" H. X 3.63" L. BOX WEIGHT: .29 LBS.