HIT36840 - 32 bit Waterprrof Steel Gear Servo -Torque 264/333/417, Speed .17/.14/.011 sec/60 degree. (4.8v, 6.0v, 7.4 volt) The steel D-840WP is part of their D-Series servo line. All Hitec D-Series servos have been designed using our brand new, cutting edge, custom engineering. Combining industry leading high-resolution, state-of-the-art ultra-response technology with a 32-bit MCU and 12-bit ADC for unprecedented programmability and flexibility, these servos deliver significantly smoother movement. The speedy, powerful line operates on a wide 4.8 ~ 8.4 voltage range, allowing use with any common battery chemistry without the need for adapters or regulators. Featuring Hitec’s 15 tooth HD output spline with 3mm hex screw, each D-Series servo brings monster performance never known before in the market.