This is the HS-7954SH High-Voltage Ultra Torque Digital Servo from Hitec.

FEATURES: Ideal for giant scale planes, large helicopters, rock crawlers, monster trucks, 1/8 scale trucks and buggies and anywhere a high performance, high torque servo is needed 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 Steel gears for much longer life than conventional metal gears Nine O-rings for extra resistance to moisture and dust Capable of operating on two cell LiPo packs

INCLUDES: HS-7954SH High-Voltage Ultra Torque Servo, 1.8" (45mm) diameter round horn, 2.3" (59mm) long double sided horn, 2.8" (72mm) long double sided horn, 1.3" (34mm) single sided horn, 0.83" (21mm) single sided aluminum horn, 0.98" (25mm) single sided horn, four each grommets, eyelets and mounting screws, instruction sheet

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

SPECS: Size: 1.57 x 0.78 x 1.45" (40 x 20 x 37mm) Weight: 2.30oz (65.2g) 6.0V 7.4V Speed: 0.15 sec 0.12 sec Torque: 333 oz/in 403 oz/in Wire Size: 22 gauge twisted wire with gold plated connectors 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: .30 LBS.