The BLS-M52B just got better and is now SR/SXR compatable.
 
The Latest and greatest from Blue Bird Precision. The BLS-M52B V2, High Voltage, Mega Torque, Helical Gears, Brushless Motor, Digital with Magnetic Hall Sensor The Powerful BLS-H51B just got better with the new Magnetic Sensored BLS-M52B!!! Smoother．More Precision．More Reliable & More Efficiency. Helical Gears for supreme strength and precision. Magnetic Sensor (Hall effect sensor, no potentiometer) Soft Start Protection Over Voltage Protection Low Voltage Protection Locked Rotor Protection Temperature Protection Includes Aluminum Servo Arm APPLICATIONS Awesome for 3D Airplane, Jet & 1/5、1/8th Monster / Crawler / Off-road Car & Helicopter. Performance Specifications Torque At 6.0V 46.2 kg-cm / 641.7 oz-in Torque At 7.4V 55.7 kg-cm / 773.6 oz-in Torque At 8.4V 62.9 kg-cm / 873.6 oz-in Speed At 6.0V 0.12 sec / 60° Speed At 7.4V 0.10 sec / 60° Speed At 8.4V 0.09 sec / 60° Protection Mechanisms Soft Start Protection Soft start to a neutral position. Over Voltage Protection Over 9.0V drive the protection mode and 8.4V return to normal mode. Low Voltage Protection Lower than 4.0V, drive the protection mode and 4.5V return to normal mode. Locked Rotor Protection Stall in 5 sec, output torque goes down. Temperature Protection Overheat 85 degrees C (185 degrees F), drive the protection mode and down 75 degrees C (167 degrees F) return to normal mode. Lose Control Protection When losing the transmitter signal, that servo will be back to the neutral position immediately and lock. Power Supply Operating Voltage Range 4.5V ~ 8.5V ( 4 ~ 6 Cell Ni-MH or 2S HV Li-Poly / 2S Li-Fe) Control Specification Control System Digital Controller / AD 12-Bits Resolution ( 4096 Steps ) Frequency：Up to 333Hz / Neutral：1500us or 1520us Dead Band Width 0.001ms ( Default：1us) Potentiometer (Variable Resistor) Magnetic Sensored 【Hall Sensor】 Mechanical Specifications Ball Bearing Dual, Stronger Ball Bearings Gear All Stainless Steel Helical Gears Outside Case Full One-Piece Aluminum CNC Casing Motor High-Efficiency Japanese Brushless Motor Horn / Gear Spline 25 Teeth ( Same as F-Type ) Dimensions and Weight Dimension (mm) 40.5 x 21 x 38.5 mm / 1.59 x 0.83 x 1.52 in Weight (gram) 83.0 ± 1 grams / 2.93 oz